upgrade ast 8.7.1

1 files changed, 0 insertions, 4448 deletions

diff --git a/ast/prism.c b/ast/prism.c
deleted file mode 100644
index 38281f3..0000000
--- a/ast/prism.c
+++ /dev/null
@@ -1,4448 +0,0 @@
-/*
-*class++
-*  Name:
-*     Prism
-
-*  Purpose:
-*     An extrusion of a region into higher dimensions.
-
-*  Constructor Function:
-c     astPrism
-f     AST_PRISM
-
-*  Description:
-*     A Prism is a Region which represents an extrusion of an existing Region
-*     into one or more orthogonal dimensions (specified by another Region).
-*     If the Region to be extruded has N axes, and the Region defining the
-*     extrusion has M axes, then the resulting Prism will have (M+N) axes.
-*     A point is inside the Prism if the first N axis values correspond to
-*     a point inside the Region being extruded, and the remaining M axis
-*     values correspond to a point inside the Region defining the extrusion.
-*
-*     As an example, a cylinder can be represented by extruding an existing
-*     Circle, using an Interval to define the extrusion. Ih this case, the
-*     Interval would have a single axis and would specify the upper and
-*     lower limits of the cylinder along its length.
-
-*  Inheritance:
-*     The Prism class inherits from the Region class.
-
-*  Attributes:
-*     The Prism class does not define any new attributes beyond those
-*     which are applicable to all Regions.
-
-*  Functions:
-c     The Prism class does not define any new functions beyond those
-f     The Prism class does not define any new routines beyond those
-*     which are applicable to all Regions.
-
-*  Copyright:
-*     Copyright (C) 1997-2006 Council for the Central Laboratory of the
-*     Research Councils
-*     Copyright (C) 2009 Science & Technology Facilities Council.
-*     All Rights Reserved.
-
-*  Licence:
-*     This program is free software: you can redistribute it and/or
-*     modify it under the terms of the GNU Lesser General Public
-*     License as published by the Free Software Foundation, either
-*     version 3 of the License, or (at your option) any later
-*     version.
-*
-*     This program is distributed in the hope that it will be useful,
-*     but WITHOUT ANY WARRANTY; without even the implied warranty of
-*     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-*     GNU Lesser General Public License for more details.
-*
-*     You should have received a copy of the GNU Lesser General
-*     License along with this program.  If not, see
-*     <http://www.gnu.org/licenses/>.
-
-*  Authors:
-*     DSB: David S. Berry (Starlink)
-
-*  History:
-*     17-DEC-2004 (DSB):
-*        Original version.
-*     11-MAY-2005 (DSB):
-*        Overlap modified to allow testing of overlap between prisms and
-*        intervals.
-*     14-FEB-2006 (DSB):
-*        Override astGetObjSize.
-*     9-OCT-2007 (DSB):
-*        Guard against all axes being extrusion axes in EquivPrism.
-*     20-JAN-2009 (DSB):
-*        Over-ride astRegBasePick.
-*     22-JAN-2009 (DSB):
-*        - Allow any class of Region to be used to define the extrusion axes.
-*        - Over-ride the astMapList method.
-*     19-MAR-2009 (DSB):
-*        Over-ride the astDecompose method.
-*     14-AUG-2014 (DSB):
-*        Over-ride the astGetRegionBounds method.
-*     9-SEP-2014 (DSB):
-*        Record the pointer to the Prism implementation of RegBaseMesh
-*        within the class virtual function table.
-*class--
-*/
-
-/* Module Macros. */
-/* ============== */
-/* Set the name of the class we are implementing. This indicates to
-   the header files that define class interfaces that they should make
-   "protected" symbols available. */
-#define astCLASS Prism
-
-/* Include files. */
-/* ============== */
-/* Interface definitions. */
-/* ---------------------- */
-
-#include "globals.h"             /* Thread-safe global data access */
-#include "error.h"               /* Error reporting facilities */
-#include "memory.h"              /* Memory allocation facilities */
-#include "object.h"              /* Base Object class */
-#include "pointset.h"            /* Sets of points/coordinates */
-#include "region.h"              /* Regions (parent class) */
-#include "channel.h"             /* I/O channels */
-#include "prism.h"               /* Interface definition for this class */
-#include "cmpmap.h"              /* Compound Mappings */
-#include "cmpframe.h"            /* Compound Frames */
-#include "unitmap.h"             /* Unit Mappings */
-#include "interval.h"            /* Axis intervals */
-#include "pointlist.h"           /* Points within Frames */
-#include "permmap.h"             /* Axis permutations */
-
-/* Error code definitions. */
-/* ----------------------- */
-#include "ast_err.h"             /* AST error codes */
-
-/* C header files. */
-/* --------------- */
-#include <stdarg.h>
-#include <stddef.h>
-#include <string.h>
-#include <stdio.h>
-#include <math.h>
-#include <limits.h>
-
-/* Module Variables. */
-/* ================= */
-
-/* Address of this static variable is used as a unique identifier for
-   member of this class. */
-static int class_check;
-
-/* Pointers to parent class methods which are extended by this class. */
-static AstMapping *(* parent_simplify)( AstMapping *, int * );
-static AstPointSet *(* parent_transform)( AstMapping *, AstPointSet *, int, AstPointSet *, int * );
-static AstRegion *(* parent_getdefunc)( AstRegion *, int * );
-static double (*parent_getfillfactor)( AstRegion *, int * );
-static int (* parent_equal)( AstObject *, AstObject *, int * );
-static int (* parent_getobjsize)( AstObject *, int * );
-static int (* parent_maplist)( AstMapping *, int, int, int *, AstMapping ***, int **, int * );
-static int (* parent_overlapx)( AstRegion *, AstRegion *, int * );
-static void (* parent_clearclosed)( AstRegion *, int * );
-static void (* parent_clearmeshsize)( AstRegion *, int * );
-static void (* parent_setclosed)( AstRegion *, int, int * );
-static void (* parent_setmeshsize)( AstRegion *, int, int * );
-static void (* parent_setregfs)( AstRegion *, AstFrame *, int * );
-static void (*parent_getregionbounds)( AstRegion *, double *, double *, int * );
-static void (*parent_regclearattrib)( AstRegion *, const char *, char **, int * );
-static void (*parent_regsetattrib)( AstRegion *, const char *, char **, int * );
-
-#if defined(THREAD_SAFE)
-static int (* parent_managelock)( AstObject *, int, int, AstObject **, int * );
-#endif
-
-
-#ifdef THREAD_SAFE
-/* Define how to initialise thread-specific globals. */
-#define GLOBAL_inits \
-   globals->Class_Init = 0;
-
-/* Create the function that initialises global data for this module. */
-astMAKE_INITGLOBALS(Prism)
-
-/* Define macros for accessing each item of thread specific global data. */
-#define class_init astGLOBAL(Prism,Class_Init)
-#define class_vtab astGLOBAL(Prism,Class_Vtab)
-
-
-#include <pthread.h>
-
-
-#else
-
-
-/* Define the class virtual function table and its initialisation flag
-   as static variables. */
-static AstPrismVtab class_vtab;   /* Virtual function table */
-static int class_init = 0;       /* Virtual function table initialised? */
-
-#endif
-
-/* External Interface Function Prototypes. */
-/* ======================================= */
-/* The following functions have public prototypes only (i.e. no
-   protected prototypes), so we must provide local prototypes for use
-   within this module. */
-AstPrism *astPrismId_( void *, void *, const char *, ... );
-
-/* Prototypes for Private Member Functions. */
-/* ======================================== */
-static AstMapping *Simplify( AstMapping *, int * );
-static AstPointSet *RegBaseMesh( AstRegion *, int * );
-static AstPointSet *Transform( AstMapping *, AstPointSet *, int, AstPointSet *, int * );
-static AstRegion *GetDefUnc( AstRegion *, int * );
-static AstRegion *RegBasePick( AstRegion *this, int, const int *, int * );
-static double *RegCentre( AstRegion *this, double *, double **, int, int, int * );
-static double GetFillFactor( AstRegion *, int * );
-static int Equal( AstObject *, AstObject *, int * );
-static int GetBounded( AstRegion *, int * );
-static int GetObjSize( AstObject *, int * );
-static int MapList( AstMapping *, int, int, int *, AstMapping ***, int **, int * );
-static int Overlap( AstRegion *, AstRegion *, int * );
-static int OverlapX( AstRegion *, AstRegion *, int * );
-static int RegPins( AstRegion *, AstPointSet *, AstRegion *, int **, int * );
-static void ClearClosed( AstRegion *, int * );
-static void ClearMeshSize( AstRegion *, int * );
-static void Copy( const AstObject *, AstObject *, int * );
-static void Decompose( AstMapping *, AstMapping **, AstMapping **, int *, int *, int *, int * );
-static void Delete( AstObject *, int * );
-static void Dump( AstObject *, AstChannel *, int * );
-static void GetRegions( AstPrism *, AstRegion **, AstRegion **, int *, int * );
-static void GetRegionBounds( AstRegion *, double *, double *, int * );
-static void RegBaseBox( AstRegion *, double *, double *, int * );
-static void RegClearAttrib( AstRegion *, const char *, char **, int * );
-static void RegSetAttrib( AstRegion *, const char *, char **, int * );
-static void SetClosed( AstRegion *, int, int * );
-static void SetMeshSize( AstRegion *, int, int * );
-static void SetRegFS( AstRegion *, AstFrame *, int * );
-
-#if defined(THREAD_SAFE)
-static int ManageLock( AstObject *, int, int, AstObject **, int * );
-#endif
-
-
-/* Member functions. */
-/* ================= */
-AstRegion *astConvertToPrism_( AstRegion *this, int *status ) {
-/*
-*+
-*  Name:
-*     astConvertToPrism
-
-*  Purpose:
-*     Convert a supplied Region into a Prism if possible.
-
-*  Type:
-*     Protected function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstRegion *astConvertToPrism( AstRegion *this, int *status )
-
-*  Description:
-*     This function attempts to split the supplied Region into two
-*     regions defined within separate coordinate system. If this is
-*     possible, and if either one of the two resulting Regions can be
-*     simplified, then the two simplified Regions are joined into a Prism
-*     equivalent to the supplied Region. The Prism is then simplified and
-*     returned.
-*
-*     If the supplied Region cannot be split into two components, or if
-*     neither of the two components can eb simplified, then a clone of the
-*     supplied Region pointer is returned.
-
-*  Parameters:
-*     this
-*        Pointer to the original Region.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     A pointer to the equivalent simplified Prism, or a clone of the
-*     supplied Region pointer.
-
-*  Notes:
-*     - A NULL pointer value will be returned if this function is
-*     invoked with the AST error status set, or if it should fail for
-*     any reason.
-*-
-*/
-
-/* Local Variables: */
-   AstFrame *frm;                /* Current Frame in supplied Region */
-   AstFrame *pickfrm1;           /* Frame formed by picking current subset of axes */
-   AstFrame *pickfrm2;           /* Frame formed by picking all other axes */
-   AstMapping *junk;             /* Unused Mapping pointer */
-   AstMapping *map;              /* Base -> current Mapping */
-   AstPrism *prism;              /* Prism combining all axes */
-   AstPrism *newprism;           /* Prism combining all axes, in original Frame */
-   AstRegion *result;            /* Result pointer to return */
-   AstRegion *sp1;               /* Simplified region spanning selected axes */
-   AstRegion *sp2;               /* Simplified region spanning unselected axes */
-   AstUnitMap *um;               /* A UnitMap */
-   int *ax;                      /* Pointer to array of selecte axis indices */
-   int *perm;                    /* Axis permutation array */
-   int axis;                     /* Axis index */
-   int bitmask;                  /* Integer with set bits for selected axes */
-   int i;                        /* Loop index */
-   int mask;                     /* Integer with a set bit at current axis */
-   int nax;                      /* Number of selected axes */
-   int nin;                      /* No. of base Frame axes (Mapping inputs) */
-   int nout;                     /* No. of current Frame axes (Mapping outputs) */
-   int topmask;                  /* Integer that selects all axes */
-
-/* Initialise. */
-   result = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get the Mapping from base to current Frame. */
-   map = astGetMapping( this->frameset, AST__BASE, AST__CURRENT );
-
-/* Get the number of inputs and outputs for the Mapping. */
-   nin = astGetNin( map );
-   nout = astGetNout( map );
-
-/* Allocate memory to hold the indices of the current Frame axes in the
-   current subset */
-   ax = astMalloc( sizeof( int )* nout );
-   if( ax ) {
-
-/* We need to scan through all possible subsets of the current Frame
-   axes, looking for a subset that results in the Region being split.
-   We use the binary pattern of bits in "bitmask" to indicate if the
-   corresponding axes should be included in the subset of axes.
-   Loop round all possible combinations, until a combination is found
-   that results in a Prism being formed. */
-      topmask = pow( 2, nout );
-      for( bitmask = 1; bitmask < topmask  && !result; bitmask++ ) {
-
-/* Store the indices of the axes forming the current subset. */
-         nax = 0;
-         mask = 1;
-         for( axis = 0; axis < nout; axis++  ) {
-            if( bitmask & mask ) ax[ nax++ ] = axis;
-            mask <<= 1;
-         }
-
-/* See if the current subset of current Frame axes can be split off from
-   the Region. If it can, the Frame pointer returned by astPickAxes will identify
-   a Region. */
-         pickfrm1 = astPickAxes( this, nax, ax, &junk );
-         junk = astAnnul( junk );
-         if( astIsARegion( pickfrm1 ) ) {
-
-/* Check that the remaining (unselected) axes can also be picked into a
-   new Region. */
-            nax = 0;
-            mask = 1;
-            for( axis = 0; axis < nout; axis++  ) {
-               if( ( bitmask & mask ) == 0 ) ax[ nax++ ] = axis;
-               mask <<= 1;
-            }
-
-            pickfrm2 = astPickAxes( this, nax, ax, &junk );
-            junk = astAnnul( junk );
-            if( astIsARegion( pickfrm2 ) ) {
-
-/* See if either of these picked Regions can be simplified. */
-               sp1 = astSimplify( pickfrm1 );
-               sp2 = astSimplify( pickfrm2 );
-               if( (AstFrame *) sp1 != pickfrm1 ||
-                   (AstFrame *) sp2 != pickfrm2 ) {
-
-/* If so form a Prism containing the simplified Regions. */
-                  prism = astPrism( sp1, sp2, " ", status );
-
-/* Permute the axes of the Prism so that they are in the same order as
-   in the Box. */
-                  perm = astMalloc( sizeof( int )*nout );
-                  if( perm ) {
-
-                     for( i = 0; i < nout; i++ ) perm[ i ] = -1;
-
-                     for( i = 0; i < nax; i++ ) {
-                        perm[ ax[ i ] ] = i + ( nout - nax );
-                     }
-
-                     nax = 0;
-                     for( i = 0; i < nout; i++ ) {
-                        if( perm[ i ] == -1 ) perm[ i ] = nax++;
-                     }
-
-                     astPermAxes( prism, perm );
-                     perm = astFree( perm );
-                  }
-
-/* Put the original current Frame back in (in place of the CmpFrame
-   containined in the Prism). */
-                  frm = astGetFrame( this->frameset, AST__CURRENT );
-                  um = astUnitMap( nout, " ", status );
-                  newprism = astMapRegion( prism, um, frm );
-                  um = astAnnul( um );
-                  frm = astAnnul( frm );
-
-/* Attempt to simplify the Prism. */
-                  result = astSimplify( newprism );
-
-/* Free resources */
-                  prism = astAnnul( prism );
-                  newprism = astAnnul( newprism );
-               }
-
-               sp1 = astAnnul( sp1 );
-               sp2 = astAnnul( sp2 );
-            }
-            pickfrm2 = astAnnul( pickfrm2 );
-         }
-
-         pickfrm1 = astAnnul( pickfrm1 );
-      }
-
-      ax = astFree( ax );
-   }
-
-   map = astAnnul( map );
-
-/* If no Prism could be made, return a clone of the supplied Region
-   pointer. */
-   if( !result ) result = astClone( this );
-
-/* If an error occurred, annul the returned pointer. */
-   if ( !astOK ) result = astAnnul( result );
-
-/* Return the result. */
-   return result;
-}
-
-static void Decompose( AstMapping *this_mapping, AstMapping **map1,
-                       AstMapping **map2, int *series, int *invert1,
-                       int *invert2, int *status ) {
-/*
-*
-*  Name:
-*     Decompose
-
-*  Purpose:
-*     Decompose a Prism into two component Regions.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "cmpregion.h"
-*     void Decompose( AstMapping *this, AstMapping **map1,
-*                     AstMapping **map2, int *series,
-*                     int *invert1, int *invert2, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the protected astDecompose
-*     method inherited from the Mapping class).
-
-*  Description:
-*     This function returns pointers to two Mappings which, when applied
-*     either in series or parallel, are equivalent to the supplied Mapping.
-*
-*     Since the Frame class inherits from the Mapping class, Frames can
-*     be considered as special types of Mappings and so this method can
-*     be used to decompose either CmpMaps, CmpFrames, CmpRegions or Prisms.
-
-*  Parameters:
-*     this
-*        Pointer to the Mapping.
-*     map1
-*        Address of a location to receive a pointer to first component
-*        Mapping.
-*     map2
-*        Address of a location to receive a pointer to second component
-*        Mapping.
-*     series
-*        Address of a location to receive a value indicating if the
-*        component Mappings are applied in series or parallel. A non-zero
-*        value means that the supplied Mapping is equivalent to applying map1
-*        followed by map2 in series. A zero value means that the supplied
-*        Mapping is equivalent to applying map1 to the lower numbered axes
-*        and map2 to the higher numbered axes, in parallel.
-*     invert1
-*        The value of the Invert attribute to be used with map1.
-*     invert2
-*        The value of the Invert attribute to be used with map2.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Notes:
-*     - Any changes made to the component rames using the returned
-*     pointers will be reflected in the supplied CmpFrame.
-
-*-
-*/
-
-/* Local Variables: */
-   AstPrism *this;              /* Pointer to Prism structure */
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Obtain a pointer to the CmpMap structure. */
-   this = (AstPrism *) this_mapping;
-
-/* The components Frames of a Prism are considered to be parallel
-   Mappings. */
-   if( series ) *series = 0;
-
-/* The Frames are returned in their original order whether or not the
-   Prism has been inverted. */
-   if( map1 ) *map1 = astClone( this->region1 );
-   if( map2 ) *map2 = astClone( this->region2 );
-
-/* The invert flags dont mean anything for a Region, but we return them
-   anyway. If the Prism has been inverted, return inverted Invert flags. */
-   if( astGetInvert( this ) ) {
-      if( invert1 ) *invert1 = astGetInvert( this->region1 ) ? 0 : 1;
-      if( invert2 ) *invert2 = astGetInvert( this->region2 ) ? 0 : 1;
-
-/* If the Prism has not been inverted, return the current Invert flags. */
-   } else {
-      if( invert1 ) *invert1 = astGetInvert( this->region1 );
-      if( invert2 ) *invert2 = astGetInvert( this->region2 );
-   }
-}
-
-static int Equal( AstObject *this_object, AstObject *that_object, int *status ) {
-/*
-*  Name:
-*     Equal
-
-*  Purpose:
-*     Test if two Objects are equivalent.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     int Equal( AstObject *this_object, AstObject *that_object, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astEqual protected
-*     method inherited from the Region class).
-
-*  Description:
-*     This function returns a boolean result (0 or 1) to indicate whether
-*     two Prisms are equivalent.
-
-*  Parameters:
-*     this
-*        Pointer to the first Prism.
-*     that
-*        Pointer to the second Prism.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     One if the Prisms are equivalent, zero otherwise.
-
-*  Notes:
-*     - The Prisms are equivalent if their component Regions are
-*     equivalent and if they have the same boolean operation, negation
-*     and closed flags.
-*     - A value of zero will be returned if this function is invoked
-*     with the global status set, or if it should fail for any reason.
-*/
-
-/* Local Variables: */
-   AstPrism *that;
-   AstPrism *this;
-   int result;
-
-/* Initialise. */
-   result = 0;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Invoke the Equal method inherited from the parent Region class. This checks
-   that the Objects are both of the same class, and have the same Negated
-   and Closed flags (amongst other things). */
-   if( (*parent_equal)( this_object, that_object, status ) ) {
-
-/* Obtain pointers to the two Prism structures. */
-      this = (AstPrism *) this_object;
-      that = (AstPrism *) that_object;
-
-/* Test their first component Regions for equality. */
-      if( astEqual( this->region1, that->region1 ) ) {
-
-/* Test their second component Regions for equality. */
-         if( astEqual( this->region2, that->region2 ) ) result = 1;
-      }
-   }
-
-/* If an error occurred, clear the result value. */
-   if ( !astOK ) result = 0;
-
-/* Return the result, */
-   return result;
-}
-
-/*
-*  Name:
-*     MAKE_SET
-
-*  Purpose:
-*     Define a function to set an attribute value for a Prism.
-
-*  Type:
-*     Private macro.
-
-*  Synopsis:
-*     #include "prism.h"
-*     MAKE_SET(attribute,lattribute,type)
-
-*  Class Membership:
-*     Defined by the Prism class.
-
-*  Description:
-*     This macro expands to an implementation of a private member function
-*     of the form:
-*
-*        static void Set<Attribute>( AstRegion *this, <Type> value )
-*
-*     that sets the value of a specified Region attribute in the parent
-*     Region structure and also in the component Regions.
-
-*  Parameters:
-*     attribute
-*        Name of the attribute, as it appears in the function name.
-*     lattribute
-*        Name of the attribute, all in lower case.
-*     type
-*        The C type of the attribute.
-*/
-
-/* Define the macro. */
-#define MAKE_SET(attribute,lattribute,type) \
-static void Set##attribute( AstRegion *this_region, type value, int *status ) { \
-\
-/* Local Variables: */ \
-   AstPrism *this;         /* Pointer to the Prism structure */ \
-\
-/* Check the global error status. */ \
-   if ( !astOK ) return; \
-\
-/* Use the parent method to set the value in the parent Region structure. */ \
-   (*parent_set##lattribute)( this_region, value, status ); \
-\
-/* Also set the value in the two component Regions. */ \
-   this = (AstPrism *) this_region; \
-   astSet##attribute( this->region1, value ); \
-   astSet##attribute( this->region2, value ); \
-}
-
-/* Use the above macro to create accessors for the MeshSize and Closed
-   attributes. */
-MAKE_SET(MeshSize,meshsize,int)
-MAKE_SET(Closed,closed,int)
-
-/* Undefine the macro. */
-#undef MAKE_SET
-
-/*
-*  Name:
-*     MAKE_CLEAR
-
-*  Purpose:
-*     Define a function to clear an attribute value for a Prism.
-
-*  Type:
-*     Private macro.
-
-*  Synopsis:
-*     #include "prism.h"
-*     MAKE_CLEAR(attribute,lattribute)
-
-*  Class Membership:
-*     Defined by the Prism class.
-
-*  Description:
-*     This macro expands to an implementation of a private member function
-*     of the form:
-*
-*        static void Clear<Attribute>( AstRegion *this )
-*
-*     that sets the value of a specified Region attribute in the parent
-*     Region structure and also in the component Regions.
-
-*  Parameters:
-*     attribute
-*        Name of the attribute, as it appears in the function name.
-*     lattribute
-*        Name of the attribute, all in lower case.
-*/
-
-/* Define the macro. */
-#define MAKE_CLEAR(attribute,lattribute) \
-static void Clear##attribute( AstRegion *this_region, int *status ) { \
-\
-/* Local Variables: */ \
-   AstPrism *this;         /* Pointer to the Prism structure */ \
-\
-/* Check the global error status. */ \
-   if ( !astOK ) return; \
-\
-/* Use the parent method to clear the value in the parent Region structure. */ \
-   (*parent_clear##lattribute)( this_region, status ); \
-\
-/* Also clear the value in the two component Regions. */ \
-   this = (AstPrism *) this_region; \
-   astClear##attribute( this->region1 ); \
-   astClear##attribute( this->region2 ); \
-}
-
-/* Use the above macro to create accessors for the MeshSize and Closed
-   attributes. */
-MAKE_CLEAR(MeshSize,meshsize)
-MAKE_CLEAR(Closed,closed)
-
-/* Undefine the macro. */
-#undef MAKE_CLEAR
-
-static int GetObjSize( AstObject *this_object, int *status ) {
-/*
-*  Name:
-*     GetObjSize
-
-*  Purpose:
-*     Return the in-memory size of an Object.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     int GetObjSize( AstObject *this, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astGetObjSize protected
-*     method inherited from the parent class).
-
-*  Description:
-*     This function returns the in-memory size of the supplied Prism,
-*     in bytes.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     The Object size, in bytes.
-
-*  Notes:
-*     - A value of zero will be returned if this function is invoked
-*     with the global status set, or if it should fail for any reason.
-*/
-
-/* Local Variables: */
-   AstPrism *this;         /* Pointer to Prism structure */
-   int result;                /* Result value to return */
-
-/* Initialise. */
-   result = 0;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Obtain a pointers to the Prism structure. */
-   this = (AstPrism *) this_object;
-
-/* Invoke the GetObjSize method inherited from the parent class, and then
-   add on any components of the class structure defined by thsi class
-   which are stored in dynamically allocated memory. */
-   result = (*parent_getobjsize)( this_object, status );
-   result += astGetObjSize( this->region1 );
-   result += astGetObjSize( this->region2 );
-
-/* If an error occurred, clear the result value. */
-   if ( !astOK ) result = 0;
-
-/* Return the result, */
-   return result;
-}
-
-static int GetBounded( AstRegion *this_region, int *status ) {
-/*
-*  Name:
-*     GetBounded
-
-*  Purpose:
-*     Is the Region bounded?
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     int GetBounded( AstRegion *this, int *status )
-
-*  Class Membership:
-*     Prism method (over-rides the astGetBounded method inherited from
-*     the Region class).
-
-*  Description:
-*     This function returns a flag indicating if the Region is bounded.
-*     The implementation provided by the base Region class is suitable
-*     for Region sub-classes representing the inside of a single closed
-*     curve (e.g. Circle, Ellipse, Box, etc). Other sub-classes (such as
-*     Prism, PointList, etc ) may need to provide their own
-*     implementations.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     Non-zero if the Region is bounded. Zero otherwise.
-
-*/
-
-/* Local Variables: */
-   AstPrism *this;            /* Pointer to Prism structure */
-   AstRegion *reg1;           /* Pointer to first component Region */
-   AstRegion *reg2;           /* Pointer to second component Region */
-   int neg;                   /* Negated flag to use with the Prism */
-   int reg1b;                 /* Is the first component Region bounded?*/
-   int reg2b;                 /* Is the second component Region bounded?*/
-   int result;                /* Returned result */
-
-/* Initialise */
-   result = 0;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Get the component Regions, and the Negated value for the Prism. The
-   returned Regions represent a region within the base Frame of the FrameSet
-   encapsulated by the parent Region structure. */
-   GetRegions( this, &reg1, &reg2, &neg, status );
-
-/* If the Prism has been inverted, temporarily invert the components. */
-   if( neg ) {
-      astNegate( reg1 );
-      astNegate( reg2 );
-   }
-
-/* See if either of the component Regions is bounded. */
-   reg1b = astGetBounded( reg1 );
-   reg2b = astGetBounded( reg2 );
-
-/* If the Prism has been inverted, re-invert the components to bring them
-   back to their original states. */
-   if( neg ) {
-      astNegate( reg1 );
-      astNegate( reg2 );
-   }
-
-/* The Prism is bounded only if both of the component Regions are bounded. */
-   result = ( reg1b && reg2b );
-
-/* Free resources. */
-   reg1 = astAnnul( reg1 );
-   reg2 = astAnnul( reg2 );
-
-/* Return zero if an error occurred. */
-   if( !astOK ) result = 0;
-
-/* Return the required pointer. */
-   return result;
-}
-
-static double GetFillFactor( AstRegion *this_region, int *status ) {
-/*
-*  Name:
-*     GetFillFactor
-
-*  Purpose:
-*     Obtain the value of the FillFactor attribute for a Prism.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     double GetFillFactor( AstRegion *this, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astGetFillFactor method inherited
-*     from the Region class).
-
-*  Description:
-*     This function returns the value of the FillFactor attribute for a
-*     Prism.  A suitable default value is returned if no value has
-*     previously been set.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     The FillFactor value to use.
-
-*/
-
-/* Local Variables: */
-   AstPrism *this;
-   double f1;
-   double f2;
-   double result;
-
-/* Check the global error status. */
-   if ( !astOK ) return AST__BAD;
-
-/* Initialise. */
-   result = AST__BAD;
-
-/* Obtain a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* See if a FillFactor value has been set. If so, use the parent
-   astGetFillFactor  method to obtain it. */
-   if ( astTestFillFactor( this ) ) {
-      result = (*parent_getfillfactor)( this_region, status );
-
-/* Otherwise, we will generate a default value equal to the product of
-   the FillFactor values of the two component Regions. */
-   } else {
-      f1 = astGetFillFactor( this->region1 );
-      f2 = astGetFillFactor( this->region2 );
-      if( f1 != AST__BAD && f2 != AST__BAD ) result = f1*f2;
-   }
-
-/* If an error occurred, clear the returned value. */
-   if ( !astOK ) result = AST__BAD;
-
-/* Return the result. */
-   return result;
-}
-
-static void GetRegionBounds( AstRegion *this_region, double *lbnd,
-                             double *ubnd, int *status ){
-/*
-*
-*  Name:
-*     GetRegionBounds
-
-*  Purpose:
-*     Returns the bounding box of Prism.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "cmpregion.h"
-*     void GetRegionBounds( AstRegion *this_region, double *lbnd,
-*                           double *ubnd, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the protected astGetRegionBounds
-*     method inherited from the Region class).
-
-*  Description:
-*     This function returns the upper and lower limits of a box which just
-*     encompasses the supplied Prism. The limits are returned as axis
-*     values within the Frame represented by the Prism. The value of the
-*     Negated attribute is ignored (i.e. it is assumed that the Prism has
-*     not been negated).
-
-*  Parameters:
-*     this
-*        Pointer to the Prism.
-*     lbnd
-*        Pointer to an array in which to return the lower axis bounds
-*        covered by the Prism. It should have at least as many elements as
-*        there are axes in the Prism. If an axis has no lower limit, the
-*        returned value will be the largest possible negative value.
-*     ubnd
-*        Pointer to an array in which to return the upper axis bounds
-*        covered by the Prism. It should have at least as many elements as
-*        there are axes in the Prism. If an axis has no upper limit, the
-*        returned value will be the largest possible positive value.
-
-*  Notes:
-*    - The value of the Negated attribute is ignored (i.e. it is assumed that
-*    the Prism has not been negated).
-*    - If an axis has no extent on an axis then the lower limit will be
-*    returned larger than the upper limit. Note, this is different to an
-*    axis which has a constant value (in which case both lower and upper
-*    limit will be returned set to the constant value).
-*    - If the bounds on an axis cannot be determined, AST__BAD is returned for
-*    both upper and lower bounds
-*    - The implementation of this method for Prisms attempts to split the Prism
-*    into two separate Regions spanning indepenent sets of axes, and then uses
-*    the astGetRegionBouinds method to get the bounds on these two Regions. Care
-*    has to be taken because the Prism may have been remapped into a different
-*    Frame since it was created.
-
-*-
-*/
-
-/* Local Variables: */
-   AstFrame *cfrm1;             /* Frame spanning current axes for 1st component Region */
-   AstFrame *cfrm2;             /* Frame spanning current axes for 2nd component Region */
-   AstFrame *cfrm;              /* Current Frame for total Prism */
-   AstMapping *map1;            /* Base->Current Mapping for axes of 1st component Region */
-   AstMapping *map2;            /* Base->Current Mapping for axes of 2nd component Region */
-   AstMapping *map;             /* Case->Current mapping for total Prism */
-   AstPrism *this;              /* Pointer to Prism structure */
-   AstRegion *reg1;             /* 1st component Region Mapping into Prism's Frame */
-   AstRegion *reg2;             /* 2nd component Region Mapping into Prism's Frame */
-   int *baxes;                  /* Indicies of Base Frame axes to be picked */
-   int *caxes;                  /* Indicies of Current Frame axes to be picked */
-   int iax;                     /* Axis index */
-   int nax1;                    /* Number of axes in first component Region */
-   int nax1_out;                /* Number of current Frame axes in first component Region */
-   int nax2;                    /* Number of axes in second component Region */
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Obtain a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Initialise */
-   cfrm1 = NULL;
-   cfrm2 = NULL;
-   map1 = NULL;
-   map2 = NULL;
-   nax1_out = 0;
-
-/* The number of base-frame axes spanned by the two component Regions. */
-   nax1 = astGetNaxes( this->region1 );
-   nax2 = astGetNaxes( this->region2 );
-
-/* Work space to hold the base frame indices for a single component
-   FrameSet. */
-   baxes = astMalloc( ( nax1 + nax2 )*sizeof( int ) );
-   if( astOK ) {
-
-/* Get the Mapping from Base to Current Frame from the Prism's FrameSet,
-   and get a pointer to the current Frame. */
-      map = astGetMapping( this_region->frameset, AST__BASE, AST__CURRENT );
-      cfrm = astGetFrame( this_region->frameset, AST__CURRENT );
-
-/* Attempt to split the FrameSet encapsulated within the Prism into two -
-   one containing the axes spanned by the first component Region and
-   another containing the axes spanned by the second component Region.
-   First store the zero-based indices of the base Frame axes
-   corresponding to the first component Region. */
-      for( iax = 0; iax < nax1; iax++ ) baxes[ iax ] = iax;
-
-/* Attempt to split these inputs from the total Mapping, thus creating a
-   Mapping that converts just the axes spanned by the first component
-   Region. */
-      caxes = astMapSplit( map, nax1, baxes, &map1 );
-
-/* If the Mapping could be split, get a Frame spanning the current Frame
-   axes corresponding to the first component Region. */
-      if( caxes ) {
-         nax1_out = astGetNout( map1 );
-         cfrm1 = astPickAxes( cfrm, nax1_out, caxes, NULL );
-         caxes = astFree( caxes );
-      }
-
-/* Do the same thing for the second component Region. */
-      for( iax = 0; iax < nax2; iax++ ) baxes[ iax ] = iax + nax1;
-      caxes = astMapSplit( map, nax2, baxes, &map2 );
-      if( caxes ) {
-         cfrm2 = astPickAxes( cfrm, astGetNout( map2 ), caxes, NULL );
-         caxes = astFree( caxes );
-      }
-
-/* Free resources. */
-      cfrm = astAnnul( cfrm );
-      map = astAnnul( map );
-   }
-   baxes = astFree( baxes );
-
-/* If the Prism mapping could not be split, use the parent GetRegionBounds
-   method. */
-   if( !map1 || !map2 ) {
-      (*parent_getregionbounds)( this_region, lbnd, ubnd, status );
-
-/* Otherwise, we get the bounds of the two component Regions separately. */
-   } else {
-
-/* Remap the first component Region using the FrameSet created above. */
-      reg1 = astMapRegion( this->region1, map1, cfrm1 );
-
-/* Get the bounds of this Region, storing the results at the start of the
-   returned lbnd/ubnd arrays. */
-      astGetRegionBounds( reg1, lbnd, ubnd );
-      reg1 = astAnnul( reg1 );
-
-/* Do the same thing for the second component Region, storing the results
-   at the end of the returned lbnd/ubnd arrays. */
-      reg2 = astMapRegion( this->region2, map2, cfrm2 );
-      astGetRegionBounds( reg2, lbnd + nax1_out, ubnd + nax1_out );
-      reg2 = astAnnul( reg2 );
-
-/* What about the possibility that the axes of the Prism have been
-   permuted? */
-
-   }
-
-/* Free resources. */
-   if( map1 ) map1 = astAnnul( map1 );
-   if( map2 ) map2 = astAnnul( map2 );
-   if( cfrm1 ) cfrm1 = astAnnul( cfrm1 );
-   if( cfrm2 ) cfrm2 = astAnnul( cfrm2 );
-
-}
-
-static void GetRegions( AstPrism *this, AstRegion **reg1, AstRegion **reg2,
-                        int *neg, int *status ) {
-/*
-*
-*  Name:
-*     GetRegions
-
-*  Purpose:
-*     Get the component Regions of a Prism.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "region.h"
-*     void GetRegions( AstPrism *this, AstRegion **reg1, AstRegion **reg2,
-*                      int *neg, int *status )
-
-*  Class Membership:
-*     Prism member function
-
-*  Description:
-*     This function returns pointers to the two Regions in a Prism, together
-*     with the Negated flag for the Prism.
-*
-*     The current Frames in both the returned component Regions will be
-*     equivalent to componets of the base Frame in the FrameSet encapsulated
-*     by the parent Region structure.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism.
-*     reg1
-*        Address of a location to receive a pointer to first component
-*        Region. This is the region which is to be extruded.
-*     reg2
-*        Address of a location to receive a pointer to second component
-*        Region. This will be an Interval defining the axes along which
-*        the first Region is to be extruded.
-*     neg
-*        Pointer to an int in which to return the value of the Negated
-*        attribute of the Prism.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Notes:
-*     - The returned pointers should be annuled using astAnnul when no
-*     longer needed.
-*     - The Frames represented by the returned Regions (that is, the
-*     current Frames in their encapsulated FrameSets) are equivalent to the
-*     base Frame in the FrameSet encapsulated within the parent Region.
-*     - Any changes made to the component Regions using the returned
-*     pointers will be reflected in the supplied Prism.
-
-*-
-*/
-
-/* Initialise */
-   if( reg1 ) *reg1 = NULL;
-   if( reg2 ) *reg2 = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Store the required values.*/
-   *reg1 = astClone( this->region1 );
-   *reg2 = astClone( this->region2 );
-   *neg = astGetNegated( (AstRegion *) this );
-}
-
-static AstRegion *GetDefUnc( AstRegion *this_region, int *status ) {
-/*
-*  Name:
-*     GetDefUnc
-
-*  Purpose:
-*     Obtain a pointer to the default uncertainty Region for a given Region.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstRegion *GetDefUnc( AstRegion *this )
-
-*  Class Membership:
-*     Prism method (over-rides the astGetDefUnc method inherited from
-*     the Region class).
-
-*     This function returns a pointer to a Region which represents the
-*     default uncertainty associated with a position on the boundary of the
-*     given  Region. The returned Region refers to the base Frame within the
-*     FrameSet encapsulated by the supplied Region.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-
-*  Returned Value:
-*     A pointer to the Region. This should be annulled (using astAnnul)
-*     when no longer needed.
-
-*  Notes:
-*     - A NULL pointer will be returned if this function is invoked
-*     with the global error status set, or if it should fail for any
-*     reason.
-*/
-
-/* Local Variables: */
-   AstPrism *this;            /* Pointer to Prism structure */
-   AstRegion *bunc1;          /* Uncertainty Region for 1st component */
-   AstRegion *bunc2;          /* Uncertainty Region for 2nd component */
-   AstRegion *result;         /* Returned pointer */
-
-/* Initialise */
-   result = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Construct a default uncertainty Region from the uncertainty Regions
-   in the two component Regions. The current Frames in the component
-   Regions are equivalent to the base Frame in the parent Region structure.
-   So we may need to map the component uncertainty into the current Region of
-   the parent if required later on. */
-   bunc1 = astGetUncFrm( this->region1, AST__CURRENT );
-   bunc2 = astGetUncFrm( this->region2, AST__CURRENT );
-
-/* Combine them into a Prism. */
-   result = (AstRegion *) astPrism( bunc1, bunc2, "", status );
-
-/* Free resources. */
-   bunc1 = astAnnul( bunc1 );
-   bunc2 = astAnnul( bunc2 );
-
-/* Return NULL if an error occurred. */
-   if( !astOK ) result = astAnnul( result );
-
-/* Return the required pointer. */
-   return result;
-}
-
-void astInitPrismVtab_(  AstPrismVtab *vtab, const char *name, int *status ) {
-/*
-*+
-*  Name:
-*     astInitPrismVtab
-
-*  Purpose:
-*     Initialise a virtual function table for a Prism.
-
-*  Type:
-*     Protected function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     void astInitPrismVtab( AstPrismVtab *vtab, const char *name )
-
-*  Class Membership:
-*     Prism vtab initialiser.
-
-*  Description:
-*     This function initialises the component of a virtual function
-*     table which is used by the Prism class.
-
-*  Parameters:
-*     vtab
-*        Pointer to the virtual function table. The components used by
-*        all ancestral classes will be initialised if they have not already
-*        been initialised.
-*     name
-*        Pointer to a constant null-terminated character string which contains
-*        the name of the class to which the virtual function table belongs (it
-*        is this pointer value that will subsequently be returned by the Object
-*        astClass function).
-*-
-*/
-
-/* Local Variables: */
-   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
-   AstFrameVtab *frame;          /* Pointer to Frame component of Vtab */
-   AstMappingVtab *mapping;      /* Pointer to Mapping component of Vtab */
-   AstObjectVtab *object;        /* Pointer to Object component of Vtab */
-   AstRegionVtab *region;        /* Pointer to Region component of Vtab */
-
-/* Check the local error status. */
-   if ( !astOK ) return;
-
-/* Get a pointer to the thread specific global data structure. */
-   astGET_GLOBALS(NULL);
-
-/* Initialize the component of the virtual function table used by the
-   parent class. */
-   astInitRegionVtab( (AstRegionVtab *) vtab, name );
-
-/* Store a unique "magic" value in the virtual function table. This
-   will be used (by astIsAPrism) to determine if an object belongs to
-   this class.  We can conveniently use the address of the (static)
-   class_check variable to generate this unique value. */
-   vtab->id.check = &class_check;
-   vtab->id.parent = &(((AstRegionVtab *) vtab)->id);
-
-/* Initialise member function pointers. */
-/* ------------------------------------ */
-/* Store pointers to the member functions (implemented here) that
-   provide virtual methods for this class. */
-
-/* None. */
-
-/* Save the inherited pointers to methods that will be extended, and
-   replace them with pointers to the new member functions. */
-   object = (AstObjectVtab *) vtab;
-   mapping = (AstMappingVtab *) vtab;
-   region = (AstRegionVtab *) vtab;
-   frame = (AstFrameVtab *) vtab;
-
-   parent_getobjsize = object->GetObjSize;
-   object->GetObjSize = GetObjSize;
-
-#if defined(THREAD_SAFE)
-   parent_managelock = object->ManageLock;
-   object->ManageLock = ManageLock;
-#endif
-
-   parent_transform = mapping->Transform;
-   mapping->Transform = Transform;
-
-   parent_simplify = mapping->Simplify;
-   mapping->Simplify = Simplify;
-
-   parent_maplist = mapping->MapList;
-   mapping->MapList = MapList;
-
-   parent_getdefunc = region->GetDefUnc;
-   region->GetDefUnc = GetDefUnc;
-
-   parent_setregfs = region->SetRegFS;
-   region->SetRegFS = SetRegFS;
-
-   parent_equal = object->Equal;
-   object->Equal = Equal;
-
-   parent_clearclosed = region->ClearClosed;
-   region->ClearClosed = ClearClosed;
-
-   parent_clearmeshsize = region->ClearMeshSize;
-   region->ClearMeshSize = ClearMeshSize;
-
-   parent_setclosed = region->SetClosed;
-   region->SetClosed = SetClosed;
-
-   parent_setmeshsize = region->SetMeshSize;
-   region->SetMeshSize = SetMeshSize;
-
-   parent_getfillfactor = region->GetFillFactor;
-   region->GetFillFactor = GetFillFactor;
-
-   parent_overlapx = region->OverlapX;
-   region->OverlapX = OverlapX;
-
-   parent_regsetattrib = region->RegSetAttrib;
-   region->RegSetAttrib = RegSetAttrib;
-
-   parent_regclearattrib = region->RegClearAttrib;
-   region->RegClearAttrib = RegClearAttrib;
-
-   parent_getregionbounds = region->GetRegionBounds;
-   region->GetRegionBounds = GetRegionBounds;
-
-/* Store replacement pointers for methods which will be over-ridden by
-   new member functions implemented here. */
-   mapping->Decompose = Decompose;
-   region->RegBaseBox = RegBaseBox;
-   region->RegBaseMesh = RegBaseMesh;
-   region->RegPins = RegPins;
-   region->GetBounded = GetBounded;
-   region->RegCentre = RegCentre;
-   region->Overlap = Overlap;
-   region->RegBasePick = RegBasePick;
-
-/* Declare the copy constructor, destructor and class dump function. */
-   astSetCopy( vtab, Copy );
-   astSetDelete( vtab, Delete );
-   astSetDump( vtab, Dump, "Prism", "Region extrusion into higher dimensions" );
-
-/* If we have just initialised the vtab for the current class, indicate
-   that the vtab is now initialised, and store a pointer to the class
-   identifier in the base "object" level of the vtab. */
-   if( vtab == &class_vtab ) {
-      class_init = 1;
-      astSetVtabClassIdentifier( vtab, &(vtab->id) );
-   }
-}
-
-#if defined(THREAD_SAFE)
-static int ManageLock( AstObject *this_object, int mode, int extra,
-                       AstObject **fail, int *status ) {
-/*
-*  Name:
-*     ManageLock
-
-*  Purpose:
-*     Manage the thread lock on an Object.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "object.h"
-*     AstObject *ManageLock( AstObject *this, int mode, int extra,
-*                            AstObject **fail, int *status )
-
-*  Class Membership:
-*     CmpMap member function (over-rides the astManageLock protected
-*     method inherited from the parent class).
-
-*  Description:
-*     This function manages the thread lock on the supplied Object. The
-*     lock can be locked, unlocked or checked by this function as
-*     deteremined by parameter "mode". See astLock for details of the way
-*     these locks are used.
-
-*  Parameters:
-*     this
-*        Pointer to the Object.
-*     mode
-*        An integer flag indicating what the function should do:
-*
-*        AST__LOCK: Lock the Object for exclusive use by the calling
-*        thread. The "extra" value indicates what should be done if the
-*        Object is already locked (wait or report an error - see astLock).
-*
-*        AST__UNLOCK: Unlock the Object for use by other threads.
-*
-*        AST__CHECKLOCK: Check that the object is locked for use by the
-*        calling thread (report an error if not).
-*     extra
-*        Extra mode-specific information.
-*     fail
-*        If a non-zero function value is returned, a pointer to the
-*        Object that caused the failure is returned at "*fail". This may
-*        be "this" or it may be an Object contained within "this". Note,
-*        the Object's reference count is not incremented, and so the
-*        returned pointer should not be annulled. A NULL pointer is
-*        returned if this function returns a value of zero.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*    A local status value:
-*        0 - Success
-*        1 - Could not lock or unlock the object because it was already
-*            locked by another thread.
-*        2 - Failed to lock a POSIX mutex
-*        3 - Failed to unlock a POSIX mutex
-*        4 - Bad "mode" value supplied.
-
-*  Notes:
-*     - This function attempts to execute even if an error has already
-*     occurred.
-*/
-
-/* Local Variables: */
-   AstPrism *this;       /* Pointer to Prism structure */
-   int result;           /* Returned status value */
-
-/* Initialise */
-   result = 0;
-
-/* Check the supplied pointer is not NULL. */
-   if( !this_object ) return result;
-
-/* Obtain a pointers to the Prism structure. */
-   this = (AstPrism *) this_object;
-
-/* Invoke the ManageLock method inherited from the parent class. */
-   if( !result ) result = (*parent_managelock)( this_object, mode, extra,
-                                                fail, status );
-
-/* Invoke the astManageLock method on any Objects contained within
-   the supplied Object. */
-   if( !result ) result = astManageLock( this->region1, mode, extra, fail );
-   if( !result ) result = astManageLock( this->region2, mode, extra, fail );
-
-   return result;
-
-}
-#endif
-
-static int MapList( AstMapping *this_mapping, int series, int invert,
-                    int *nmap, AstMapping ***map_list, int **invert_list,
-                    int *status ) {
-/*
-*  Name:
-*     MapList
-
-*  Purpose:
-*     Decompose a Prism into a sequence of simpler Regions.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "mapping.h"
-*     int MapList( AstMapping *this, int series, int invert, int *nmap,
-*                  AstMapping ***map_list, int **invert_list )
-
-*  Class Membership:
-*     Prism member function (over-rides the protected astMapList
-*     method inherited from the Region class).
-
-*  Description:
-*     This function decomposes a Prism into a sequence of simpler
-*     Regions which may be applied in parallel to achieve the same
-*     effect. The Prism is decomposed as far as possible, but it is
-*     not guaranteed that this will necessarily yield any more than
-*     one Region, which may actually be the original Prism supplied.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism to be decomposed (the Prism is not
-*        actually modified by this function).
-*     series
-*        Prisms always apply their component Regions in parallel, so this
-*        value should always be zero. This function will return without
-*        action if it is non-zero.
-*     invert
-*        Inverting a Region has no effect on the properties of the Region
-*        and so this parameter is ignored.
-*     nmap
-*        The address of an int which holds a count of the number of
-*        individual Regions in the decomposition. On entry, this
-*        should count the number of Regions already in the
-*        "*map_list" array (below). On exit, it is updated to include
-*        any new Regions appended by this function.
-*     map_list
-*        Address of a pointer to an array of Region pointers. On
-*        entry, this array pointer should either be NULL (if no
-*        Regions have yet been obtained) or should point at a
-*        dynamically allocated array containing Region pointers
-*        ("*nmap" in number) which have been obtained from a previous
-*        invocation of this function.
-*
-*        On exit, the dynamic array will be enlarged to contain any
-*        new Region pointers that result from the decomposition
-*        requested. These pointers will be appended to any previously
-*        present, and the array pointer will be updated as necessary
-*        to refer to the enlarged array (any space released by the
-*        original array will be freed automatically).
-*
-*        The new Region pointers returned will identify a sequence of
-*        Regions which, when applied (in parallel) in order, will be
-*        equivalent to the original Prism.
-*
-*        All the Region pointers returned by this function should be
-*        annulled by the caller, using astAnnul, when no longer
-*        required. The dynamic array holding these pointers should
-*        also be freed, using astFree.
-*     invert_list
-*        Address of a pointer to an array of int. On entry, this array
-*        pointer should either be NULL (if no Regions have yet been
-*        obtained) or should point at a dynamically allocated array
-*        containing Invert attribute values ("*nmap" in number) which
-*        have been obtained from a previous invocation of this
-*        function.
-*
-*        On exit, the dynamic array will be enlarged to contain any
-*        new Invert attribute values that result from the
-*        decomposition requested. These values will be appended to any
-*        previously present, and the array pointer will be updated as
-*        necessary to refer to the enlarged array (any space released
-*        by the original array will be freed automatically).
-*
-*        The new Invert values returned will always be zero since a
-*        Region is unaffected by its Invert setting.
-*
-*        The dynamic array holding these values should be freed by the
-*        caller, using astFree, when no longer required.
-
-*  Returned Value:
-*     Zero is always returned.
-
-*  Notes:
-*     - It is unspecified to what extent the original Prism and the
-*     individual (decomposed) Regions are
-*     inter-dependent. Consequently, the individual Regions cannot be
-*     modified without risking modification of the original Prism.
-*     - If this function is invoked with the global error status set,
-*     or if it should fail for any reason, then the *nmap value, the
-*     list of Region pointers and the list of Invert values will all
-*     be returned unchanged.
-*/
-
-/* Local Variables: */
-   AstPrism *this;              /* Pointer to Prism structure */
-
-/* Check the global error status. */
-   if ( !astOK ) return 0;
-
-/* Obtain a pointer to the Prism structure. */
-   this = (AstPrism *) this_mapping;
-
-/* When considered as a CmpMap, a Prism always combines its component
-   Mappings (Regions) in parallel. So check that a parallel decomposition
-   was requested. */
-   if ( ! series ) {
-
-/* Concatenate the Mapping lists obtained from each component Region. */
-      (void) astMapList( (AstMapping *) this->region1, 0, 0, nmap, map_list,
-                         invert_list );
-      (void) astMapList( (AstMapping *) this->region2, 0, 0, nmap, map_list,
-                         invert_list );
-
-/* If the Prism does not combine its components in the way required
-   by the decomposition (series or parallel), then we cannot decompose
-   it. In this case it must be appended to the Mapping list as a
-   single entity. We can use the parent class method to do this. */
-   } else {
-      (void) ( *parent_maplist )( this_mapping, series, invert, nmap,
-                                  map_list, invert_list, status );
-   }
-
-   return 0;
-}
-
-static int Overlap( AstRegion *this, AstRegion *that, int *status ){
-/*
-*  Name:
-*     Overlap
-
-*  Purpose:
-*     Test if two regions overlap each other.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     int Overlap( AstRegion *this, AstRegion *that, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astOverlap method inherited
-*     from the Region class).
-
-*  Description:
-*     This function returns an integer value indicating if the two
-*     supplied Regions overlap. The two Regions are converted to a commnon
-*     coordinate system before performing the check. If this conversion is
-*     not possible (for instance because the two Regions represent areas in
-*     different domains), then the check cannot be performed and a zero value
-*     is returned to indicate this.
-
-*  Parameters:
-*     this
-*        Pointer to the first Region.
-*     that
-*        Pointer to the second Region.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     astOverlap()
-*        A value indicating if there is any overlap between the two Regions.
-*        Possible values are:
-*
-*        0 - The check could not be performed because the second Region
-*            could not be mapped into the coordinate system of the first
-*            Region.
-*
-*        1 - There is no overlap between the two Regions.
-*
-*        2 - The first Region is completely inside the second Region.
-*
-*        3 - The second Region is completely inside the first Region.
-*
-*        4 - There is partial overlap between the two Regions.
-*
-*        5 - The Regions are identical.
-*
-*        6 - The second Region is the negation of the first Region.
-
-*  Notes:
-*     - The returned values 5 and 6 do not check the value of the Closed
-*     attribute in the two Regions.
-*     - A value of zero will be returned if this function is invoked with the
-*     AST error status set, or if it should fail for any reason.
-
-*/
-
-/* Local Variables: */
-   AstFrame *bfrm;
-   AstFrame *efrm;
-   AstFrameSet *fs;
-   AstMapping *bmap;
-   AstMapping *emap;
-   AstMapping *map1;
-   AstMapping *map2;
-   AstMapping *map;
-   AstMapping *smap;
-   AstRegion *that_base2;
-   AstRegion *that_base;
-   AstRegion *that_ext2;
-   AstRegion *that_ext;
-   AstRegion *this_reg1;
-   AstRegion *this_reg2;
-   int *inax;
-   int *outax;
-   int i;
-   int nbase;
-   int next;
-   int rbase;
-   int result;
-   int rext;
-   int that_neg;
-   int this_neg;
-
-/* A table indicating how to combine together the overlap state of the
-   extrusion Regions with the overlap state of the other (base) Region.
-   The first index represents the value returned by the astOverlap method
-   when used to determine the overlap of the base Regions in the two
-   supplied Prisms. The second index represents the value returned by the
-   astOverlap method when used to determine the overlap of the extrusion
-   Regions in the two supplied Prisms. The integer values stored in the
-   array represent the astOverlap value describing the overlap of the two
-   Prisms. */
-   static int rtable[ 7 ][ 7 ] = { { 0, 0, 0, 0, 0, 0, 0 },
-                                   { 0, 1, 1, 1, 1, 1, 1 },
-                                   { 0, 1, 2, 4, 4, 2, 1 },
-                                   { 0, 1, 4, 3, 4, 3, 1 },
-                                   { 0, 1, 4, 4, 4, 4, 1 },
-                                   { 0, 1, 2, 3, 4, 5, 1 },
-                                   { 0, 1, 1, 1, 1, 1, 6 } };
-
-/* Initialise */
-   result = 0;
-
-/* Check the inherited status. */
-   if ( !astOK ) return result;
-
-/* Get pointers to the base and extrusion Regions within "this", and also
-   the nagated flag. */
-   GetRegions( (AstPrism *) this, &this_reg1, &this_reg2, &this_neg, status );
-
-/* Get the number of axes in the base and extrusion Regions of "this". */
-   nbase = astGetNaxes( this_reg1 );
-   next = astGetNaxes( this_reg2 );
-
-/* Get a FrameSet which goes from the Frame represented by "this" to the
-   Frame represented by "that". Check that the conection is defined. */
-   fs = astConvert( this, that, "" );
-   if( fs ) {
-
-/* Get the forward Mapping from the above FrameSet. */
-      map2 = astGetMapping( fs, AST__BASE, AST__CURRENT );
-
-/* Get a pointer to the Mapping from base to current Frame in "this". */
-      map1 = astGetMapping( this->frameset, AST__BASE, AST__CURRENT );
-
-/* Combine these Mappings to get the Mapping from the base Frame of "this"
-   to the current Frame of "that". */
-      map = (AstMapping *) astCmpMap( map1, map2, 1, "", status );
-
-/* Simplify this Mapping. */
-      smap = astSimplify( map );
-
-/* See if the extrusion axes in "this" correspond to a unique set of axes
-   in the current Frame of "that". */
-      inax = astMalloc( sizeof(int)*(size_t)next );
-      for( i = 0; i < next; i++ ) inax[ i ] = nbase + i;
-      outax = astMapSplit( smap, next, inax, &emap );
-
-/* If they do, attempt to create a Region by picking the axes from "that"
-   that correspond to the extrusion axes in "this". */
-      if( emap && astGetNout( emap ) == next ) {
-         that_ext = (AstRegion *) astPickAxes( that, next, outax, NULL );
-
-/* If the picked axes formed a Region, see if the base axes can also be
-   picked in the same way. */
-         if( astIsARegion( that_ext ) ) {
-            outax = astFree( outax );
-            inax = astGrow( inax, (size_t)nbase, sizeof( int ) );
-            for( i = 0; i < nbase; i++ ) inax[ i ] = i;
-            outax = astMapSplit( smap, nbase, inax, &bmap );
-            if( bmap && astGetNout( bmap ) == nbase ) {
-               that_base = (AstRegion *) astPickAxes( that, nbase, outax, NULL );
-               if( astIsARegion( that_base ) ) {
-
-/* Map the two Regions picked from "that" into the Frames of the two
-   sub-regions within "this". */
-                  astInvert( emap );
-                  efrm = astGetFrame( this_reg2->frameset, AST__CURRENT );
-                  that_ext2 = astMapRegion( that_ext, emap, efrm );
-
-                  astInvert( bmap );
-                  bfrm = astGetFrame( this_reg1->frameset, AST__CURRENT );
-                  that_base2 = astMapRegion( that_base, bmap, bfrm );
-
-/* We can test separately for overlap of the two extrusion Regions, and for
-   overlap of the two base Regions, and then combine the returned flags to
-   represent overlap of the whole Prism. */
-                  rbase = astOverlap( this_reg1, that_base2 );
-                  rext = astOverlap( this_reg2, that_ext2 );
-                  result = rtable[ rbase ][ rext ];
-
-/* The values in the rtable array assume that neither of the supplied
-   Prisms have been negated. Modify the value obtained from rtable to
-   take account of negation of either or both of the supplied Prisms. */
-                  that_neg = astGetNegated( that );
-                  if( this_neg ) {
-                     if( that_neg ) {
-                        if( result == 1 ) {
-                           result = 4;
-                        } else if( result == 2 ) {
-                           result = 3;
-                        } else if( result == 3 ) {
-                           result = 2;
-                        }
-                     } else {
-                        if( result == 1 ) {
-                           result = 3;
-                        } else if( result == 2 ) {
-                           result = 4;
-                        } else if( result == 3 ) {
-                           result = 1;
-                        } else if( result == 5 ) {
-                           result = 6;
-                        } else if( result == 6 ) {
-                           result = 5;
-                        }
-                     }
-                  } else if( that_neg ){
-                     if( result == 1 ) {
-                        result = 2;
-                     } else if( result == 2 ) {
-                        result = 1;
-                     } else if( result == 3 ) {
-                        result = 4;
-                     } else if( result == 5 ) {
-                        result = 6;
-                     } else if( result == 6 ) {
-                        result = 5;
-                     }
-                  }
-
-/* Free resources */
-                  efrm = astAnnul( efrm );
-                  that_ext2 = astAnnul( that_ext2 );
-                  bfrm = astAnnul( bfrm );
-                  that_base2 = astAnnul( that_base2 );
-               }
-               that_base = astAnnul( that_base );
-               bmap = astAnnul( bmap );
-            }
-         }
-         emap = astAnnul( emap );
-         that_ext = astAnnul( that_ext );
-      }
-      outax = astFree( outax );
-      inax = astFree( inax );
-      smap = astAnnul( smap );
-      map = astAnnul( map );
-      map1 = astAnnul( map1 );
-      map2 = astAnnul( map2 );
-      fs = astAnnul( fs );
-   }
-   this_reg1 = astAnnul( this_reg1 );
-   this_reg2 = astAnnul( this_reg2 );
-
-/* If overlap could not be determined using the above implementation, try
-   using the implementation inherited from the parent Region class. Use
-   OverlapX rather than Overlap since a) it is OverlapX that does the work,
-   and b) calling Overlap could end us in an infinite loop. */
-   if( !result ) result = (*parent_overlapx)( this, that, status );
-
-/* If not OK, return zero. */
-   if( !astOK ) result = 0;
-
-/* Return the result. */
-   return result;
-}
-
-static int OverlapX( AstRegion *that, AstRegion *this, int *status ){
-/*
-*  Name:
-*     OverlapX
-
-*  Purpose:
-*     Test if two regions overlap each other.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     int OverlapX( AstRegion *that, AstRegion *this )
-
-*  Class Membership:
-*     Prism member function (over-rides the astOverlapX method inherited
-*     from the Region class).
-
-*  Description:
-*     This function performs the processing for the public astOverlap
-*     method and has exactly the same interface except that the order
-*     of the two arguments is swapped. This is a trick to allow
-*     the astOverlap method to be over-ridden by derived classes on
-*     the basis of the class of either of its two arguments.
-*
-*     See the astOverlap method for details of the interface.
-*/
-
-/* Local Variables; */
-   int result;
-
-/* Check the global error status. */
-   if ( !astOK ) return 0;
-
-/* We know that "that" is a Prism, so call the private Overlap method,
-   and then modify the returned value to take account of the fact that the
-   two Regions are swapped. */
-   result = Overlap( that, this, status );
-
-   if( result == 2 ){
-      result = 3;
-   } else if( result == 3 ){
-      result = 2;
-   }
-
-   return result;
-}
-
-
-static void RegBaseBox( AstRegion *this_region, double *lbnd, double *ubnd,
-                        int *status ){
-/*
-*  Name:
-*     RegBaseBox
-
-*  Purpose:
-*     Returns the bounding box of an un-negated Region in the base Frame of
-*     the encapsulated FrameSet.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     void RegBaseBox( AstRegion *this, double *lbnd, double *ubnd,
-*                      int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astRegBaseBox protected
-*     method inherited from the Region class).
-
-*  Description:
-*     This function returns the upper and lower axis bounds of a Region in
-*     the base Frame of the encapsulated FrameSet, assuming the Region
-*     has not been negated. That is, the value of the Negated attribute
-*     is ignored.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     lbnd
-*        Pointer to an array in which to return the lower axis bounds
-*        covered by the Region in the base Frame of the encapsulated
-*        FrameSet. It should have at least as many elements as there are
-*        axes in the base Frame.
-*     ubnd
-*        Pointer to an array in which to return the upper axis bounds
-*        covered by the Region in the base Frame of the encapsulated
-*        FrameSet. It should have at least as many elements as there are
-*        axes in the base Frame.
-*     status
-*        Pointer to the inherited status variable.
-
-*/
-
-/* Local Variables: */
-   AstPrism *this;              /* Pointer to Prism structure */
-   AstRegion *reg1;             /* Pointer to first component Region */
-   AstRegion *reg2;             /* Pointer to second component Region */
-   int nax;                     /* Number of axes in Frame */
-   int neg;                     /* Negated flag for Prism */
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Get a pointer to the Prism structure */
-   this = (AstPrism *) this_region;
-
-/* Get pointers to the component Regions. */
-   GetRegions( this, &reg1, &reg2, &neg, status );
-
-/* The base Frame of the parent Region structure is equivalent to a
-   CmpFrame containing the current Frames of the component Regions.
-   Get the no. of axes in the first component Frame. */
-   nax = astGetNaxes( reg1 );
-
-/* Get the bounding boxes of the component Regions in these Frame,
-   storing the values in the supplied arrays. */
-   astGetRegionBounds( reg1, lbnd, ubnd );
-   astGetRegionBounds( reg2, lbnd + nax, ubnd + nax );
-
-/* Free resources.*/
-   reg1 = astAnnul( reg1 );
-   reg2 = astAnnul( reg2 );
-}
-
-static AstPointSet *RegBaseMesh( AstRegion *this_region, int *status ){
-/*
-*  Name:
-*     RegBaseMesh
-
-*  Purpose:
-*     Return a PointSet containing a mesh of points on the boundary of a
-*     Region in its base Frame.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstPointSet *RegBaseMesh( AstRegion *this, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astRegBaseMesh protected
-*     method inherited from the Region class).
-
-*  Description:
-*     This function returns a PointSet containing a mesh of points on the
-*     boundary of the Region. The points refer to the base Frame of
-*     the encapsulated FrameSet.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     Pointer to the PointSet. Annul the pointer using astAnnul when it
-*     is no longer needed.
-
-*  Notes:
-*    - A NULL pointer is returned if an error has already occurred, or if
-*    this function should fail for any reason.
-
-*/
-
-
-/* Local Variables: */
-   AstPointSet *grid1;            /* PointSet holding grid for region1 */
-   AstPointSet *grid2;            /* PointSet holding grid for region2 */
-   AstPointSet *mesh1;            /* PointSet holding mesh for region1 */
-   AstPointSet *mesh2;            /* PointSet holding mesh for region2 */
-   AstPointSet *result;           /* Returned pointer */
-   AstPrism *this;                /* The Prism structure */
-   AstRegion *reg1;               /* Pointer to first component Region */
-   AstRegion *reg2;               /* Pointer to second component Region */
-   double **pg1;                  /* Pointer to grid1 arrays */
-   double **pg2;                  /* Pointer to grid2 arrays */
-   double **pm1;                  /* Pointer to mesh1 arrays */
-   double **pm2;                  /* Pointer to mesh2 arrays */
-   double **ptr;                  /* Pointer to returned mesh arrays */
-   int gsz1;                      /* Preferred grid size for region1 */
-   int gsz2;                      /* Preferred grid size for region2 */
-   int hasMesh1;                  /* Does 1st component Region have a mesh? */
-   int hasMesh2;                  /* Does 2nd component Region have a mesh? */
-   int i;                         /* Index of next mesh position */
-   int ii;                        /* Index of next results position */
-   int j;                         /* Index of next grid position */
-   int jc;                        /* Axis index */
-   int msz1;                      /* Preferred mesh size for region1 */
-   int msz2;                      /* Preferred mesh size for region2 */
-   int msz;                       /* Original MeshSize */
-   int mszp;                      /* MeshSize value for Prism */
-   int nax1;                      /* Number of axes in region1 */
-   int nax2;                      /* Number of axes in region2 */
-   int nax;                       /* Number of axes in Prism */
-
-/* Initialise */
-   result= NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* If the Region structure contains a pointer to a PointSet holding
-   a previously created mesh, return it. */
-   if( this_region->basemesh ) {
-      result = astClone( this_region->basemesh );
-
-/* Otherwise, create a new mesh. */
-   } else {
-
-/* Get pointers to the component regions. */
-      reg1 = this->region1;
-      reg2 = this->region2;
-
-/* A mesh can only be produced for a Region if it is bounded when either
-   negated or un-negated. See if meshes can be produced for the component
-   Regions. */
-      hasMesh1 = astGetBounded( reg1 );
-      if( !hasMesh1 ){
-         astNegate( reg1 );
-         hasMesh1 = astGetBounded( reg1 );
-         astNegate( reg1 );
-      }
-
-      hasMesh2 = astGetBounded( reg2 );
-      if( !hasMesh2 ){
-         astNegate( reg2 );
-         hasMesh2 = astGetBounded( reg2 );
-         astNegate( reg2 );
-      }
-
-/* If either Region does not have a mesh we cannot produce a mesh for the
-   Prism. */
-      if( !hasMesh1 || !hasMesh2 ) {
-         if( astOK ) astError( AST__INTER, "astRegBaseMesh(%s): No mesh "
-                   "can be produced for the %s bacause one of its component "
-                   "Regions is unbounded.", status, astGetClass( this ), astGetClass( this ) );
-
-/* Otherwise we can create a mesh for the Prism. */
-      } else {
-
-/* Determine the grid sizes and mesh sizes to use for the two components.
-   This aims to produce a total number of points in the returned Prism
-   mesh roughly equal to the MeshSize attribute of the Prism. It also
-   aims to divide the mesh points equally between the end faces of the
-   prism, and the side walls. We remember that the grid used to represent
-   any 1-D region always has a size of 2, regardless of the setting of
-   MeshSize. */
-         mszp = astGetMeshSize( this );
-         msz1 = ( astGetNaxes( reg1 ) == 1 ) ? 2 : sqrt( 0.5*mszp );
-         gsz2 = 0.5*mszp/msz1;
-         msz2 = ( astGetNaxes( reg2 ) == 1 ) ? 2 : sqrt( 0.5*mszp );
-         gsz1 = 0.5*mszp/msz2;
-
-/* First, get a boundary mesh for the second component Region defining the
-   prism extrusion. For instance, if the Region is 1-dimensional, this mesh
-   will consist of the two values on the Region axis: the lower and upper
-   bounds of the Region. */
-         msz = astTestMeshSize( reg2 ) ? astGetMeshSize( reg2 ) : -1;
-         astSetMeshSize( reg2, msz2 );
-         mesh2 = astRegMesh( reg2 );
-
-/* Also get a grid of points spread throughout the extent (i.e. not
-   merely on the boundary) of the second Region. */
-         astSetMeshSize( reg2, gsz2 );
-         grid2 = astRegGrid( reg2 );
-
-/* Re-instate the original MeshSize for the second Region. */
-         if( msz == -1 ) {
-            astClearMeshSize( reg2 );
-         } else {
-            astSetMeshSize( reg2, msz );
-         }
-
-/* Similarly, get a boundary mesh and a volume grid for the first Region. */
-         msz = astTestMeshSize( reg1 ) ? astGetMeshSize( reg1 ) : -1;
-         astSetMeshSize( reg1, msz1 );
-         mesh1 = astRegMesh( reg1 );
-
-         astSetMeshSize( reg1, gsz1 );
-         grid1 = astRegGrid( reg1 );
-
-         if( msz == -1 ) {
-            astClearMeshSize( reg1 );
-         } else {
-            astSetMeshSize( reg1, msz );
-         }
-
-/* Note the number of axes in the two component Regions. */
-         nax1 = astGetNcoord( mesh1 );
-         nax2 = astGetNcoord( mesh2 );
-
-/* The above mesh and grid sizes are only approximate. Find the values
-   actually used. */
-         msz1 = astGetNpoint( mesh1 );
-         gsz1 = astGetNpoint( grid1 );
-         msz2 = astGetNpoint( mesh2 );
-         gsz2 = astGetNpoint( grid2 );
-
-/* Create the returned PointSet. */
-         msz = gsz1*msz2 + msz1*gsz2;
-         nax= astGetNaxes( this );
-         result = astPointSet( msz, nax, "", status );
-
-/* Get pointers to the data in all 5 PointSets. */
-         ptr = astGetPoints( result );
-         pm1 = astGetPoints( mesh1 );
-         pg1 = astGetPoints( grid1 );
-         pm2 = astGetPoints( mesh2 );
-         pg2 = astGetPoints( grid2 );
-
-/* Check pointers can be de-referenced safely. */
-         if( astOK ) {
-
-/* Initialise the index of the next point to be written to the results
-   array. */
-            ii = 0;
-
-/* First, replicate the volume grid covering the first region at every
-   point in the boundary mesh covering the second Region. */
-            for( i = 0; i < msz2; i++ ) {
-               for( j = 0; j < gsz1; j++, ii++ ) {
-                  for( jc = 0; jc < nax1; jc++ ) {
-                     ptr[ jc ][ ii ] = pg1[ jc ][ j ];
-                  }
-                  for( ; jc < nax; jc++ ) {
-                     ptr[ jc ][ ii ] = pm2[ jc - nax1 ][ i ];
-                  }
-               }
-            }
-
-/* Now, replicate the volume grid covering the second region at every
-   point in the boundary mesh covering the first Region. */
-            for( i = 0; i < msz1; i++ ) {
-               for( j = 0; j < gsz2; j++, ii++ ) {
-                  for( jc = 0; jc < nax1; jc++ ) {
-                     ptr[ jc ][ ii ] = pm1[ jc ][ i ];
-                  }
-                  for( ; jc < nax; jc++ ) {
-                     ptr[ jc ][ ii ] = pg2[ jc -nax1 ][ j ];
-                  }
-               }
-            }
-         }
-
-/* Free resources. */
-         mesh1 = astAnnul( mesh1 );
-         mesh2 = astAnnul( mesh2 );
-         grid1 = astAnnul( grid1 );
-         grid2 = astAnnul( grid2 );
-      }
-
-/* Save the returned pointer in the Region structure so that it does not
-   need to be created again next time this function is called. */
-      if( astOK && result ) this_region->basemesh = astClone( result );
-   }
-
-/* Annul the result if an error has occurred. */
-   if( !astOK ) result = astAnnul( result );
-
-/* Return a pointer to the output PointSet. */
-   return result;
-}
-
-static AstRegion *RegBasePick( AstRegion *this_region, int naxes,
-                               const int *axes, int *status ){
-/*
-*  Name:
-*     RegBasePick
-
-*  Purpose:
-*     Return a Region formed by picking selected base Frame axes from the
-*     supplied Region.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstRegion *RegBasePick( AstRegion *this, int naxes, const int *axes,
-*                             int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astRegBasePick protected
-*     method inherited from the Region class).
-
-*  Description:
-*     This function attempts to return a Region that is spanned by selected
-*     axes from the base Frame of the encapsulated FrameSet of the supplied
-*     Region. This may or may not be possible, depending on the class of
-*     Region. If it is not possible a NULL pointer is returned.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     naxes
-*        The number of base Frame axes to select.
-*     axes
-*        An array holding the zero-based indices of the base Frame axes
-*        that are to be selected.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     Pointer to the Region, or NULL if no region can be formed.
-
-*  Notes:
-*    - A NULL pointer is returned if an error has already occurred, or if
-*    this function should fail for any reason.
-*/
-
-/* Local Variables: */
-   AstFrame *frm1;      /* Axes picked from the 1st encapsulated Region */
-   AstFrame *frm2;      /* Axes picked from the 2nd encapsulated Region */
-   AstPrism *this;      /* Pointer to Prism structure */
-   AstRegion *result;   /* Returned Region */
-   int *axes1;          /* Axes to pick from 1st input encapsulated Region */
-   int *axes2;          /* Axes to pick from 2nd input encapsulated Region */
-   int i;               /* Output axis index */
-   int j;               /* Input axis index */
-   int nax1;            /* No. of axes in 1st input encapsulated Region */
-   int nax2;            /* No. of axes in 2nd input encapsulated Region */
-   int naxes1;          /* No. of axes in 1st output encapsulated Region */
-   int naxes2;          /* No. of axes in 2nd output encapsulated Region */
-
-/* Initialise */
-   result = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get a pointer to the Prism information. */
-   this = (AstPrism *) this_region;
-
-/* Get the number of axes in each of the two encapsulated Regions. */
-   nax1 = astGetNaxes( this->region1 );
-   nax2 = astGetNaxes( this->region2 );
-
-/* Allocate memory to hold the indices of the axes selected from each of
-   the two encapsulated Regions. */
-   axes1 = astMalloc( sizeof( *axes1 )*nax1 );
-   axes2 = astMalloc( sizeof( *axes2 )*nax2 );
-
-/* Check pointers can be used safely. */
-   if( astOK ) {
-
-/* Initialise the counters that count the number of axes selected from
-   each of the two encapsulated Regions. */
-      naxes1 = 0;
-      naxes2 = 0;
-
-/* For each of the axes to be selected from the prism... */
-      for( i = 0; i < naxes; i++ ) {
-         j = axes[ i ];
-
-/* ... if the current selected axis is part of the first encapsulated
-   Region, add its index into the array that holds the axes to be selected
-   from the first encapsulated region. Increment the number of axes
-   selected from the first encapsulated region. */
-         if( j < nax1 ) {
-            axes1[ naxes1++ ] = j;
-
-/* If the current selected axis is part of the second encapsulated Region,
-   add its index into the array that holds the axes to be selected from
-   the second encapsulated region. Note, the index is converted from a
-   Prism axis index to a sub-region axis index by subtracting "nax1".
-   Also increment the number of axes selected from the second encapsulated
-   region. */
-         } else {
-            axes2[ naxes2++ ] = j - nax1;
-         }
-      }
-
-/* Pick any required axes from the first sub-region. If the result of the
-   selection is not a Region, we cannot pick the required axes, so annul
-   the object holding the selected axes. */
-      if( naxes1 ) {
-         frm1 = astPickAxes( this->region1, naxes1, axes1, NULL );
-         if( frm1 && !astIsARegion( frm1 ) ) frm1 = astAnnul( frm1 );
-      } else {
-         frm1 = NULL;
-      }
-
-/* Pick any required axes from the second sub-region. If the result of the
-   selection is not a Region, we cannot pick the required axes, so annul
-   the object holding the selected axes. */
-      if( naxes2 ) {
-         frm2 = astPickAxes( this->region2, naxes2, axes2, NULL );
-         if( frm2 && !astIsARegion( frm2 ) ) frm2 = astAnnul( frm2 );
-      } else {
-         frm2 = NULL;
-      }
-
-/* If we are selecting axes only from the first sub-region, and the above
-   selection was succesful, just return a clone of the Region holding the
-   axes selected from the first sub-region. */
-      if( naxes1 > 0 && naxes2 == 0 && frm1 ) {
-         result = astClone( frm1 );
-
-/* If we are selecting axes only from the second sub-region, and the above
-   selection was succesful, just return a clone of the Region holding the
-   axes selected from the second sub-region. */
-      } else if( naxes1 == 0 && naxes2 > 0 && frm2 ) {
-         result = astClone( frm2 );
-
-/* If we are selecting axes from both sub-regions, and both the above
-   selections were succesful, joing them together into a Prism. */
-      } else if( naxes1 > 0 && naxes2 > 0 && frm1 && frm2 ) {
-         result = (AstRegion *) astPrism( (AstRegion *) frm1,
-                                          (AstRegion *) frm2,
-                                          "", status );
-      }
-
-/* Free resources */
-      if( frm1 ) frm1 = astAnnul( frm1 );
-      if( frm2 ) frm2 = astAnnul( frm2 );
-   }
-
-   axes1 = astFree( axes1 );
-   axes2 = astFree( axes2 );
-
-/* Return a NULL pointer if an error has occurred. */
-   if( !astOK ) result = astAnnul( result );
-
-/* Return the result. */
-   return result;
-}
-
-static double *RegCentre( AstRegion *this_region, double *cen, double **ptr,
-                          int index, int ifrm, int *status ){
-/*
-*  Name:
-*     RegCentre
-
-*  Purpose:
-*     Re-centre a Region.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     double *RegCentre( AstRegion *this, double *cen, double **ptr,
-*                        int index, int ifrm, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astRegCentre protected
-*     method inherited from the Region class).
-
-*  Description:
-*     This function shifts the centre of the supplied Region to a
-*     specified position, or returns the current centre of the Region.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     cen
-*        Pointer to an array of axis values, giving the new centre.
-*        Supply a NULL value for this in order to use "ptr" and "index" to
-*        specify the new centre.
-*     ptr
-*        Pointer to an array of points, one for each axis in the Region.
-*        Each pointer locates an array of axis values. This is the format
-*        returned by the PointSet method astGetPoints. Only used if "cen"
-*        is NULL.
-*     index
-*        The index of the point within the arrays identified by "ptr" at
-*        which is stored the coords for the new centre position. Only used
-*        if "cen" is NULL.
-*     ifrm
-*        Should be AST__BASE or AST__CURRENT. Indicates whether the centre
-*        position is supplied and returned in the base or current Frame of
-*        the FrameSet encapsulated within "this".
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     If both "cen" and "ptr" are NULL then a pointer to a newly
-*     allocated dynamic array is returned which contains the centre
-*     coords of the Region. This array should be freed using astFree when
-*     no longer needed. If either of "ptr" or "cen" is not NULL, then a
-*     NULL pointer is returned.
-
-*  Notes:
-*    - Some Region sub-classes do not have a centre. Such classes will report
-*    an AST__INTER error code if this method is called with either "ptr" or
-*    "cen" not NULL. If "ptr" and "cen" are both NULL, then no error is
-*    reported if this method is invoked on a Region of an unsuitable class,
-*    but NULL is always returned.
-*/
-
-/* Local Variables: */
-   AstPrism *this;     /* Pointer to Prism structure */
-   AstRegion *reg1;    /* Pointer to first component Region */
-   AstRegion *reg2;    /* Pointer to second component Region */
-   double *bc;         /* Base Frame centre position */
-   double *cen1;       /* Centre of first component Region */
-   double *cen2;       /* Centre of second component Region */
-   double *result;     /* Returned pointer */
-   double *tmp;        /* Temporary array pointer */
-   double *total;      /* Pointer to total base Frame centre array */
-   int i;              /* Coordinate index */
-   int nax1;           /* Number of axes in first component Region */
-   int nax2;           /* Number of axes in second component Region */
-   int ncb;            /* Number of base frame coordinate values per point */
-   int ncc;            /* Number of current frame coordinate values per point */
-   int neg;            /* Prism negated flag */
-
-/* Initialise */
-   result = NULL;
-
-/* Check the local error status. */
-   if ( !astOK ) return result;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Get the component Regions, and the Negated flag for the Prism. */
-   GetRegions( this, &reg1, &reg2, &neg, status );
-
-/* Get the number of current Frame axes in each component Region. The sum
-   of these will equal the number of base Frame axes in the parent Region
-   structure. */
-   nax1 = astGetNaxes( reg1 );
-   nax2 = astGetNaxes( reg2 );
-   ncb = nax1 + nax2;
-
-/* If we are getting (not setting) the current centre... */
-   if( !ptr && !cen ) {
-
-/* Get the centre from the two component Regions in their current Frames. */
-      cen1 = astRegCentre( reg1, NULL, NULL, 0, AST__CURRENT );
-      cen2 = astRegCentre( reg2, NULL, NULL, 0, AST__CURRENT );
-
-/* If both component regions are re-centerable, join the two centre
-   arrays together into a single array. */
-      if( cen1 && cen2 ) {
-         total = astMalloc( sizeof(double)*(size_t)ncb );
-         if( total ) {
-            for( i = 0; i < nax1; i++ ) total[ i ] = cen1[ i ];
-            for( i = 0; i < nax2; i++ ) total[ i + nax1 ] = cen2[ i ];
-
-/* The current Frames of the component Regions correspond to the base
-   Frame of the parent Region structure. If the original centre is
-   required in the current Frame, transform it using the base->current
-   Mapping from the parent Region structure. */
-            if( ifrm == AST__CURRENT ) {
-               result = astRegTranPoint( this_region, total, 1, 1 );
-               total = astFree( total );
-            } else {
-               result = total;
-            }
-         }
-      }
-
-/* Free the individual centre arrays. */
-      cen1 = astFree( cen1 );
-      cen2 = astFree( cen2 );
-
-/* If we are setting a new centre... */
-   } else {
-
-/* If the new centre is supplied in the current Frame of the parent
-   Region structure, transform it into the base Frame (i.e. the Frames
-   represented by the component Regions). */
-      if( ifrm == AST__CURRENT ) {
-         if( cen ) {
-            bc = astRegTranPoint( this_region, cen, 1, 0 );
-         } else {
-            ncc = astGetNaxes( this_region );
-            tmp = astMalloc( sizeof( double)*(size_t)ncc );
-            if( astOK ) {
-               for( i = 0; i < ncc; i++ ) tmp[ i ] = ptr[ i ][ index ];
-            }
-            bc = astRegTranPoint( this_region, tmp, 1, 0 );
-            tmp = astFree( tmp );
-         }
-
-      } else {
-         if( cen ) {
-            bc = cen;
-         } else {
-            bc = astMalloc( sizeof( double)*(size_t)ncb );
-            if( astOK ) {
-               for( i = 0; i < ncb; i++ ) bc[ i ] = ptr[ i ][ index ];
-            }
-         }
-      }
-
-/* Set the centre in the two component Regions in their current Frames. */
-      astRegCentre( reg1, bc, NULL, 0, AST__CURRENT );
-      astRegCentre( reg2, bc + nax1, NULL, 0, AST__CURRENT );
-
-/* Free resources. */
-     if( bc != cen ) bc = astFree( bc );
-   }
-
-   reg1 = astAnnul( reg1 );
-   reg2 = astAnnul( reg2 );
-
-/* Return the result. */
-   return result;
-}
-
-static int RegPins( AstRegion *this_region, AstPointSet *pset, AstRegion *unc,
-                    int **mask, int *status ){
-/*
-*  Name:
-*     RegPins
-
-*  Purpose:
-*     Check if a set of points fall on the boundary of a given Prism.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     int RegPins( AstRegion *this, AstPointSet *pset, AstRegion *unc,
-*                  int **mask, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astRegPins protected
-*     method inherited from the Region class).
-
-*  Description:
-*     This function returns a flag indicating if the supplied set of
-*     points all fall on the boundary of the given Prism.
-*
-*     Some tolerance is allowed, as specified by the uncertainty Region
-*     stored in the supplied Prism "this", and the supplied uncertainty
-*     Region "unc" which describes the uncertainty of the supplied points.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism.
-*     pset
-*        Pointer to the PointSet. The points are assumed to refer to the
-*        base Frame of the FrameSet encapsulated by "this".
-*     unc
-*        Pointer to a Region representing the uncertainties in the points
-*        given by "pset". The Region is assumed to represent the base Frame
-*        of the FrameSet encapsulated by "this". Zero uncertainity is assumed
-*        if NULL is supplied.
-*     mask
-*        Pointer to location at which to return a pointer to a newly
-*        allocated dynamic array of ints. The number of elements in this
-*        array is equal to the value of the Npoint attribute of "pset".
-*        Each element in the returned array is set to 1 if the
-*        corresponding position in "pset" is on the boundary of the Region
-*        and is set to zero otherwise. A NULL value may be supplied
-*        in which case no array is created. If created, the array should
-*        be freed using astFree when no longer needed.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     Non-zero if the points all fall on the boundary of the given
-*     Region, to within the tolerance specified. Zero otherwise.
-
-*/
-
-/* Local variables: */
-   AstPointSet *ps1;            /* Points projected into 1st component Region */
-   AstPointSet *ps1b;           /* "ps1" in base Frame of 1st component Region */
-   AstPointSet *ps1b2;          /* "ps1b" transformed using 1st Region */
-   AstPointSet *ps2b2;          /* "ps2b" transformed using 2nd Region */
-   AstPointSet *ps2;            /* Points projected into 2nd component Region */
-   AstPointSet *ps2b;           /* "ps2" in base Frame of 2nd component Region */
-   AstPrism *this;              /* Pointer to the Prism structure. */
-   AstRegion *reg1;             /* Pointer to first component Region */
-   AstRegion *reg2;             /* Pointer to second component Region */
-   AstRegion *unc1;             /* Base Frame uncertainty in 1st component Region */
-   AstRegion *unc2;             /* Base Frame uncertainty in 2nd component Region */
-   double **ptr1b2;             /* Pointer to axis values in "ps1b2" */
-   double **ptr2b2;             /* Pointer to axis values in "ps2b2" */
-   int *mask1;                  /* Mask for first component boundary */
-   int *mask2;                  /* Mask for second component boundary */
-   int cl1;                     /* Original Closed flag for reg1 */
-   int cl2;                     /* Original Closed flag for reg2 */
-   int i;                       /* Point index */
-   int j;                       /* Axis index */
-   int nax1;                    /* Number of axes in first component Region */
-   int nax2;                    /* Number of axes in second component Region */
-   int np;                      /* Number of points in supplied PointSet */
-   int on;                      /* Is this point on the Prism boundary? */
-   int result;                  /* Returned flag */
-
-/* Initialise */
-   result = 0;
-   if( mask ) *mask = NULL;
-
-/* Check the inherited status. */
-   if( !astOK ) return result;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Get pointers to the two component Regions. */
-   reg1 = this->region1;
-   reg2 = this->region2;
-
-/* Temporarily ensure the components are closed. */
-   cl1 = astTestClosed( reg1 ) ? astGetClosed( reg1 ) : INT_MAX;
-   cl2 = astTestClosed( reg2 ) ? astGetClosed( reg2 ) : INT_MAX;
-   astSetClosed( reg1, cl1 );
-   astSetClosed( reg2, cl2 );
-
-/* A point in the coordinate system represented by the Prism is on the
-   boundary of the Prism if:
-   1) it is on the boundary of one of the coomponent Regions AND
-   2) it is on or within the boundary of the other component Region.
-
-   First look for points on the boundary of the first component Region.
-   Create a PointSet holding just the axes from the supplied PointSet
-   which relate to the first component Region. */
-   np = astGetNpoint( pset );
-   nax1 = astGetNaxes( reg1 );
-   ps1 = astPointSet( np, nax1, "", status );
-   astSetSubPoints( pset, 0, 0, ps1 );
-
-/* Get a mask which indicates if each supplied point is on or off the
-   boundary of the first component Region. astRegPins expects its "pset"
-   argument to contain positions in the base Frame of the Region, so
-   we must first transform the supplied points into the base Frame of
-   "reg1". We must also get the uncertainty in the base Frame of the
-   component Region. */
-   ps1b = astRegTransform( reg1, ps1, 0, NULL, NULL );
-   unc1 = astGetUncFrm( reg1, AST__BASE );
-   astRegPins( reg1, ps1b, unc1, &mask1 );
-
-/* Also determine which of the points are on or in the boundary by using
-   "reg1" as a Mapping to transform the supplied points. */
-   ps1b2 = astTransform( reg1, ps1b, 1, NULL );
-
-/* Do the same for the second component Region */
-   nax2 = astGetNaxes( reg2 );
-   ps2 = astPointSet( np, nax2, "", status );
-   astSetSubPoints( pset, 0, nax1, ps2 );
-   ps2b = astRegTransform( reg2, ps2, 0, NULL, NULL );
-   unc2 = astGetUncFrm( reg2, AST__BASE );
-   astRegPins( reg2, ps2b, unc2, &mask2 );
-   ps2b2 = astTransform( reg2, ps2b, 1, NULL );
-
-/* Get pointers to the data in all the relevant PointSets. */
-   ptr1b2 = astGetPoints( ps1b2 );
-   ptr2b2 = astGetPoints( ps2b2 );
-
-/* Check pointers can be dereferenced safely. */
-   if( astOK ) {
-
-/* Assume all points are on the boundary of the Prism. */
-      result = 1;
-
-/* Check each point. */
-      for( i = 0; i < np; i++ ) {
-
-/* Assume this point is on the boundary of the Prism. */
-         on = 1;
-
-/* If this point is on the boundary of both component Regions, it is on
-   the boundary of the Prism. If it is on the boundary of the first
-   component Region but not on the boundary of the second, then it is
-   still on the boundary of the Prism if it is within the volume
-   reporesented by the second. */
-         if( mask1[ i ] ) {
-            if( !mask2[ i ] ) {
-               for( j = 0; j < nax2; j++ ) {
-                  if( ptr2b2[ j ][ i ] == AST__BAD ) {
-                     on = 0;
-                     break;
-                  }
-               }
-            }
-
-/* If this point is on the boundary of the second component Region but
-   not the first, it is on the boundary of the Prism if it is within the
-   volume reporesented by the first. */
-         } else {
-            if( mask2[ i ] ) {
-               for( j = 0; j < nax1; j++ ) {
-                  if( ptr1b2[ j ][ i ] == AST__BAD ) {
-                     on = 0;
-                     break;
-                  }
-               }
-
-/* If this point is on the boundary of neither component Region, it is not
-   on the boundary of the Prism. */
-            } else {
-               on = 0;
-            }
-         }
-
-/* Use "mask1" to return the Prism's mask. Clear the returned flag if
-   this point is not on the boundary of the Prism. */
-         mask1[ i ] = on;
-         if( !on ) result = 0;
-      }
-   }
-
-/* Re-instate the original values of the Closed attribute for the
-   component Regions. */
-   if( cl1 == INT_MAX ) {
-      astClearClosed( reg1 );
-   } else {
-      astSetClosed( reg1, cl1 );
-   }
-   if( cl2 == INT_MAX ) {
-      astClearClosed( reg2 );
-   } else {
-      astSetClosed( reg2, cl2 );
-   }
-
-/* Return "mask1" as the Prism's mask if required. Otherwise free it. */
-   if( mask ) {
-      *mask = mask1;
-   } else {
-      mask1 = astFree( mask1 );
-   }
-
-/* Free other resources */
-   mask2 = astFree( mask2 );
-   ps1 = astAnnul( ps1 );
-   ps1b = astAnnul( ps1b );
-   ps1b2 = astAnnul( ps1b2 );
-   ps2 = astAnnul( ps2 );
-   unc1 = astAnnul( unc1 );
-   ps2b = astAnnul( ps2b );
-   ps2b2 = astAnnul( ps2b2 );
-   unc2 = astAnnul( unc2 );
-
-/* If an error has occurred, return zero. */
-   if( !astOK ) {
-      result = 0;
-      if( mask ) *mask = astFree( *mask );
-   }
-
-/* Return the result. */
-   return result;
-}
-
-static void RegClearAttrib( AstRegion *this_region, const char *attrib,
-                            char **base_attrib, int *status ) {
-/*
-*  Name:
-*     RegClearAttrib
-
-*  Purpose:
-*     Clear an attribute value for a Region.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     void RegClearAttrib( AstRegion *this, const char *attrib,
-*                          char **base_attrib, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astRegClearAttrib method
-*     inherited from the Region class).
-
-*  Description:
-*     This function clears the value of a named attribute in both the base
-*     and current Frame in the FrameSet encapsulated within a Region, without
-*     remapping either Frame.
-*
-*     No error is reported if the attribute is not recognised by the base
-*     Frame.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     attrib
-*        Pointer to a null terminated string holding the attribute name.
-*        NOTE, IT SHOULD BE ENTIRELY LOWER CASE.
-*     base_attrib
-*        Address of a location at which to return a pointer to the null
-*        terminated string holding the attribute name which was cleared in
-*        the base Frame of the encapsulated FrameSet. This may differ from
-*        the supplied attribute if the supplied attribute contains an axis
-*        index and the current->base Mapping in the FrameSet produces an
-*        axis permutation. The returned pointer should be freed using
-*        astFree when no longer needed. A NULL pointer may be supplied in
-*        which case no pointer is returned.
-*     status
-*        Pointer to the inherited status variable.
-
-*/
-
-/* Local Variables: */
-   AstPrism *this;
-   AstRegion *creg;
-   char *batt;
-   char buf1[ 100 ];
-   char buf2[ 255 ];
-   int axis;
-   int len;
-   int nax1;
-   int nc;
-   int rep;
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Use the RegClearAttrib method inherited from the parent class to clear the
-   attribute in the current and base Frames in the FrameSet encapsulated by
-   the parent Region structure. */
-   (*parent_regclearattrib)( this_region, attrib, &batt, status );
-
-/* We now propagate the setting down to the component Regions. The current
-   Frames in the component Regions together form a CmpFrame which is
-   equivalent to the base Frame in the parent FrameSet. Switch off error
-   reporting whilst we apply the setting to the component Regions. */
-   rep = astReporting( 0 );
-
-/* If the setting which was applied to the base Frame of the parent FrameSet
-   is qualified by an axis index, modify the axis index to refer to component
-   Region which defines the axis. First parse the base Frame attribute setting
-   to locate any axis index. */
-   len = strlen( batt );
-   if( nc = 0, ( 2 == astSscanf( batt, "%[^(](%d) %n", buf1, &axis,
-                                 &nc ) ) && ( nc >= len ) ) {
-
-/* If found, convert the axis index from one-based to zero-based. */
-      axis--;
-
-/* Get a pointer to the component Region containing the specified axis, and
-   create a new setting with the same attribute name but with the axis index
-   appropriate to the component Region which defines the axis. */
-      nax1 = astGetNaxes( this->region1 );
-      if( axis < nax1 ) {
-         creg = this->region1;
-      } else {
-         creg = this->region2;
-         axis -= nax1;
-      }
-      sprintf( buf2, "%s(%d)", buf1, axis + 1 );
-
-/* Apply the setting to the relevant component Region. */
-      astRegClearAttrib( creg, buf2, NULL );
-
-/* If the setting is not qualified by an axis index, apply it to both
-   component Regions. */
-   } else {
-      astRegClearAttrib( this->region1, batt, NULL );
-      astRegClearAttrib( this->region2, batt, NULL );
-   }
-
-/* Annul the error if the attribute was not recognised by the component
-   Regions. Then switch error reporting back on. */
-   if( astStatus == AST__BADAT ) astClearStatus;
-   astReporting( rep );
-
-/* If required, return the base Frame setting string. Otherwise free it. */
-   if( base_attrib ) {
-      *base_attrib = batt;
-   } else {
-      batt = astFree( batt );
-   }
-
-}
-
-static void RegSetAttrib( AstRegion *this_region, const char *setting,
-                          char **base_setting, int *status ) {
-/*
-*  Name:
-*     RegSetAttrib
-
-*  Purpose:
-*     Set an attribute value for a Region.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     void RegSetAttrib( AstRegion *this, const char *setting,
-*                        char **base_setting, int *status )
-
-*  Class Membership:
-*     Prism method (over-rides the astRegSetAttrib method inherited from
-*     the Region class).
-
-*  Description:
-*     This function assigns an attribute value to both the base and
-*     current Frame in the FrameSet encapsulated within a Region, without
-*     remapping either Frame.
-*
-*     No error is reported if the attribute is not recognised by the base
-*     Frame.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     setting
-*        Pointer to a null terminated attribute setting string. NOTE, IT
-*        SHOULD BE ENTIRELY LOWER CASE. The supplied string will be
-*        interpreted using the public interpretation implemented by
-*        astSetAttrib. This can be different to the interpretation of the
-*        protected accessor functions. For instance, the public
-*        interpretation of an unqualified floating point value for the
-*        Epoch attribute is to interpet the value as a gregorian year,
-*        but the protected interpretation is to interpret the value as an
-*        MJD.
-*     base_setting
-*        Address of a location at which to return a pointer to the null
-*        terminated attribute setting string which was applied to the
-*        base Frame of the encapsulated FrameSet. This may differ from
-*        the supplied setting if the supplied setting contains an axis
-*        index and the current->base Mapping in the FrameSet produces an
-*        axis permutation. The returned pointer should be freed using
-*        astFree when no longer needed. A NULL pointer may be supplied in
-*        which case no pointer is returned.
-*     status
-*        Pointer to the inherited status variable.
-
-*/
-
-/* Local Variables: */
-   AstPrism *this;
-   AstRegion *creg;
-   char *bset;
-   char buf1[ 100 ];
-   char buf2[ 255 ];
-   int axis;
-   int len;
-   int nax1;
-   int nc;
-   int rep;
-   int value;
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Get a pointer to the Prism structure. */
-   this = (AstPrism *) this_region;
-
-/* Use the RegSetAttrib method inherited from the parent class to apply the
-   setting to the current and base Frames in the FrameSet encapsulated by the
-   parent Region structure. */
-   (*parent_regsetattrib)( this_region, setting, &bset, status );
-
-/* We now propagate the setting down to the component Regions. The current
-   Frames in the component Regions together form a CmpFrame which is
-   equivalent to the base Frame in the parent FrameSet. Switch off error
-   reporting whilst we apply the setting to the component Regions. */
-   rep = astReporting( 0 );
-
-/* If the setting which was applied to the base Frame of the parent FrameSet
-   is qualified by an axis index, modify the axis index to refer to component
-   Region which defines the axis. First parse the base Frame attribute setting
-   to locate any axis index. */
-   len = strlen( bset );
-   if( nc = 0, ( 2 == astSscanf( bset, "%[^(](%d)= %n%*s %n", buf1, &axis,
-                                 &value, &nc ) ) && ( nc >= len ) ) {
-
-/* If found, convert the axis index from one-based to zero-based. */
-      axis--;
-
-/* Get a pointer to the component Region containing the specified axis, and
-   create a new setting with the same attribute name but with the axis index
-   appropriate to the component Region which defines the axis. */
-      nax1 = astGetNaxes( this->region1 );
-      if( axis < nax1 ) {
-         creg = this->region1;
-      } else {
-         creg = this->region2;
-         axis -= nax1;
-      }
-      sprintf( buf2, "%s(%d)=%s", buf1, axis + 1, bset + value );
-
-/* Apply the setting to the relevant component Region. */
-      astRegSetAttrib( creg, buf2, NULL );
-
-/* If the setting is not qualified by an axis index, apply it to both
-   component Regions. */
-   } else {
-      astRegSetAttrib( this->region1, bset, NULL );
-      astRegSetAttrib( this->region2, bset, NULL );
-   }
-
-/* Annul the error if the attribute was not recognised by the component
-   Regions. Then switch error reporting back on. */
-   if( astStatus == AST__BADAT ) astClearStatus;
-   astReporting( rep );
-
-/* If required, return the base Frame setting string. Otherwise free it. */
-   if( base_setting ) {
-      *base_setting = bset;
-   } else {
-      bset = astFree( bset );
-   }
-
-}
-
-static void SetRegFS( AstRegion *this_region, AstFrame *frm, int *status ) {
-/*
-*  Name:
-*     SetRegFS
-
-*  Purpose:
-*     Stores a new FrameSet in a Region
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     void SetRegFS( AstRegion *this_region, AstFrame *frm, int *status )
-
-*  Class Membership:
-*     Prism method (over-rides the astSetRegFS method inherited from
-*     the Region class).
-
-*  Description:
-*     This function creates a new FrameSet and stores it in the supplied
-*     Region. The new FrameSet contains two copies of the supplied
-*     Frame, connected by a UnitMap.
-
-*  Parameters:
-*     this
-*        Pointer to the Region.
-*     frm
-*        The Frame to use.
-*     status
-*        Pointer to the inherited status variable.
-
-*/
-
-/* Local Variables: */
-   AstFrame *cfrm;         /* Frame containing required axes */
-   AstRegion *creg;        /* Pointer to component Region structure */
-   int *axes;              /* Pointer to array of axis indices */
-   int i;                  /* Loop count */
-   int nax1;               /* No.of axes in 1st component Frame */
-   int nax2;               /* No.of axes in 2nd component Frame */
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Invoke the parent method to store the FrameSet in the parent Region
-   structure. */
-   (* parent_setregfs)( this_region, frm, status );
-
-/* If either component Region has a dummy FrameSet use this method
-   recursively to give them a FrameSet containing the corresponding axes
-   from the supplied Frame. */
-   creg = ((AstPrism *) this_region )->region1;
-   if( creg ) {
-      nax1 = astGetNaxes( creg );
-      if( !astGetRegionFS( creg ) ) {
-         axes = astMalloc( sizeof( int )*(size_t) nax1 );
-         if( astOK ) for( i = 0; i < nax1; i++ ) axes[ i ] = i;
-         cfrm = astPickAxes( frm, nax1, axes, NULL );
-         astSetRegFS( creg, cfrm );
-         axes = astFree( axes );
-         cfrm = astAnnul( cfrm );
-      }
-
-   } else {
-      nax1 = 0;
-   }
-
-   creg = ((AstPrism *) this_region )->region2;
-   if( creg && !astGetRegionFS( creg ) ) {
-      nax2 = astGetNaxes( creg );
-      axes = astMalloc( sizeof( int )*(size_t) nax2 );
-      if( astOK ) for( i = 0; i < nax2; i++ ) axes[ i ] = nax1 + i;
-      cfrm = astPickAxes( frm, nax2, axes, NULL );
-      astSetRegFS( creg, cfrm );
-      axes = astFree( axes );
-      cfrm = astAnnul( cfrm );
-   }
-
-}
-
-static AstMapping *Simplify( AstMapping *this_mapping, int *status ) {
-/*
-*  Name:
-*     Simplify
-
-*  Purpose:
-*     Simplify a Region.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "region.h"
-*     AstMapping *Simplify( AstMapping *this, int *status )
-
-*  Class Membership:
-*     Prism method (over-rides the astSimplify method inherited from
-*     the Region class).
-
-*  Description:
-*     This function simplifies a Prism to eliminate redundant
-*     computational steps, or to merge separate steps which can be
-*     performed more efficiently in a single operation.
-
-*  Parameters:
-*     this
-*        Pointer to the original Region.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     A new pointer to the (possibly simplified) Region.
-
-*  Notes:
-*     - A NULL pointer value will be returned if this function is
-*     invoked with the AST error status set, or if it should fail for
-*     any reason.
-
-*  Deficiencies:
-*     - Currently, this function does not attempt to map the component
-*     Regions into the current Frame of the parent Region structure.
-
-*/
-
-/* Local Variables: */
-   AstFrame *cfrm;               /* Current Frame */
-   AstFrame *newfrm1;            /* Current Frame axes for reg1 */
-   AstFrame *newfrm2;            /* Current Frame axes for reg2 */
-   AstFrameSet *fs;              /* Parent FrameSet */
-   AstMapping *bcmap;            /* Base->current Mapping */
-   AstMapping *nmap1;            /* Reg1->current Mapping */
-   AstMapping *map1;             /* First component Region from a CmpMap */
-   AstMapping *map2;             /* Second component Region from a CmpMap */
-   int series;                   /* Apply component Mappings in series? */
-   int invert1;                  /* Use inverted first component Mapping? */
-   int invert2;                  /* Use inverted second component Mapping? */
-   AstMapping *nmap2;            /* Reg2->current Mapping */
-   AstMapping *result;           /* Result pointer to return */
-   AstCmpMap *cmpmap;            /* Result pointer to return */
-   AstMapping *smap;             /* Simplified CmpMap */
-   AstRegion *new2;              /* New simplified Region */
-   AstRegion *new;               /* New Region */
-   AstRegion *newreg1;           /* Reg1 mapped into current Frame */
-   AstRegion *newreg2;           /* Reg2 mapped into current Frame */
-   AstRegion *reg1;              /* First component Region */
-   AstRegion *reg2;              /* Second component Region */
-   AstRegion *reg;               /* This Region */
-   AstRegion *snewreg1;          /* Simplified newreg1 */
-   AstRegion *snewreg2;          /* Simplified newreg2 */
-   AstRegion *unc;               /* Uncertainty Region from supplied Prism */
-   int *axin;                    /* Indices of Mapping inputs to use */
-   int *axout1;                  /* Indices of cfrm axes corresponding to reg1 */
-   int *axout2;                  /* Indices of cfrm axes corresponding to reg2 */
-   int *perm;                    /* Axis permutation array */
-   int i;                        /* Loop count */
-   int nax1;                     /* Number of axes in first component Region */
-   int nax2;                     /* Number of axes in second component Region */
-   int naxt;                     /* Total number of axes in current Frame */
-   int naxout1;                  /* Number of current axes for reg1 */
-   int naxout2;                  /* Number of current axes for reg2 */
-   int neg;                      /* Negated flag for supplied Prism */
-
-/* Initialise. */
-   result = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get a pointer to the Region structure */
-   reg = (AstRegion *) this_mapping;
-
-/* Get the component Regions, and the Negated flag for the Prism. */
-   GetRegions( (AstPrism *) this_mapping, &reg1, &reg2, &neg, status );
-
-/* The above Regions describe areas within the base Frame of the FrameSet
-   encapsulated by the parent Region structure. Get the current Frame in
-   this FrameSet and the base->current Mapping. */
-   fs = reg->frameset;
-   cfrm = astGetFrame( fs, AST__CURRENT );
-   bcmap = astGetMapping( fs, AST__BASE, AST__CURRENT );
-
-/* Combine the two Regions into a parallel CmpMap (this uses the fact
-   that a Region is a type of Mapping). Then simplify the CmpMap. This
-   will result in the astMapMerge methods defined by sub-classes of
-   Regions being used to merge adjacent regions. */
-   cmpmap = astCmpMap( reg1, reg2, 0, "", status );
-   smap = astSimplify( cmpmap );
-   cmpmap = astAnnul( cmpmap );
-
-/* Initially, assume we cannot form a new Region from the simplified
-   CmpMap. */
-   new = NULL;
-
-/* If the result is a region, use it. */
-   if( astIsARegion( smap ) ) {
-      new = astClone( smap );
-
-/* If the result is a parallel CmpMap, get its two components and check
-   they are Regions. If so, and if they are not the same as the original
-   two component Regions, form a new Prism from them. */
-   } else if( astIsACmpMap( smap ) ) {
-      astDecompose( smap, &map1, &map2, &series, &invert1, &invert2  );
-      if( ! series && astIsARegion( map1 ) && astIsARegion( map2 ) ) {
-         if( (AstRegion *) map1 != reg1 || (AstRegion *) map2 != reg2 ) {
-            new = (AstRegion *) astPrism( (AstRegion *) map1,
-                                          (AstRegion *) map2, "", status );
-         }
-      }
-
-/* Free resources */
-      map1 = astAnnul( map1 );
-      map2 = astAnnul( map2 );
-   }
-
-   smap = astAnnul( smap );
-
-/* If the above produced a simplified Region, map it into the current Frame
-   of "this" and simplify it. */
-   if( new ) {
-      new2 = astMapRegion( new, bcmap, cfrm );
-      (void) astAnnul( new );
-      new = astSimplify( new2 );
-      new2 = astAnnul( new2 );
-
-/* If the above did not produced a result, try a different approach. */
-   } else {
-
-/* Get the number of axes in each component Region. */
-      nax1 = astGetNaxes( reg1 );
-      nax2 = astGetNaxes( reg2 );
-
-/* Use astMapSplit to see if the axes of the first component Region correspond
-   to a distinct set of axes within the current Frame. If this is the case,
-   then a Mapping is returned by astMapSplit which  maps the axes of the first
-   component Region into the corresponding current Frame axes. Also returned
-   is a list of the axes within the current Frame which correspnd to the
-   axes of the first component Region. */
-      nmap1 = NULL;
-      axout1 = NULL;
-      axin = astMalloc( sizeof( int )*(size_t)nax1 );
-      if( astOK ) {
-         for( i = 0; i < nax1; i++ ) axin[ i ] = i;
-         axout1 = astMapSplit( bcmap, nax1, axin, &nmap1 );
-         axin = astFree( axin );
-      }
-
-/* Do the same for the second component. */
-      nmap2 = NULL;
-      axout2 = NULL;
-      axin = astMalloc( sizeof( int )*(size_t)nax2 );
-      if( astOK ) {
-         for( i = 0; i < nax2; i++ ) axin[ i ] = i + nax1;
-         axout2 = astMapSplit( bcmap, nax2, axin, &nmap2 );
-         axin = astFree( axin );
-      }
-
-/* Assume for the moment that the component Regions cannot be simplified.
-   In this case we will use a clone of the supplied Prism. */
-      new = astClone( this_mapping );
-
-/* Determine the number of outputs from these Mappings. */
-      if( nmap1 ){
-         naxout1 = astGetNout( nmap1 );
-      } else {
-         naxout1 = 0;
-      }
-      if( nmap2 ){
-         naxout2 = astGetNout( nmap2 );
-      } else {
-         naxout2 = 0;
-      }
-
-/* Determine the number of axes in the current Frame of the Prism. */
-      naxt = astGetNout( bcmap );
-
-/* If the second component does not contribute any axes to the total
-   Prism, we can ignore it. */
-      if( naxout1 == naxt && naxout2 == 0 ) {
-         newfrm1 = astPickAxes( cfrm, naxout1, axout1, NULL );
-         newreg1 = astMapRegion( reg1, nmap1, newfrm1 );
-         (void) astAnnul( new );
-         new = astSimplify( newreg1 );
-         if( neg ) astNegate( new );
-         perm = astMalloc( sizeof( int )*(size_t) ( naxout1 ) );
-         if( astOK ) {
-            for( i = 0; i < naxout1; i++ ) perm[ i ] = axout1[ i ];
-            astPermAxes( new, perm );
-            perm = astFree( perm );
-         }
-         newfrm1 = astAnnul( newfrm1 );
-         newreg1 = astAnnul( newreg1 );
-
-/* If the first component does not contribute any axes to the total
-   Prism, we can ignore it. */
-      } else if( naxout1 == 0 && naxout2 == naxt ) {
-         newfrm2 = astPickAxes( cfrm, naxout2, axout2, NULL );
-         newreg2 = astMapRegion( reg2, nmap2, newfrm2 );
-         (void) astAnnul( new );
-         new = astSimplify( newreg2 );
-         if( neg ) astNegate( new );
-         perm = astMalloc( sizeof( int )*(size_t) ( naxout2 ) );
-         if( astOK ) {
-            for( i = 0; i < naxout2; i++ ) perm[ i ] = axout2[ i ];
-            astPermAxes( new, perm );
-            perm = astFree( perm );
-         }
-         newfrm2 = astAnnul( newfrm2 );
-         newreg2 = astAnnul( newreg2 );
-
-/* If both component Regions correspond to a distinct subspace within the
-   current Frame, then we can try to express each component Region within
-   the current Frame. */
-      } else if( nmap1 && nmap2 ) {
-
-/* Create a Frame representing the subspace of the current Frame which
-   corresponds to the axes of the first component Region. */
-         newfrm1 = astPickAxes( cfrm, naxout1, axout1, NULL );
-
-/* Remap the first component Region so that it represents an area in this
-   subspace. */
-         newreg1 = astMapRegion( reg1, nmap1, newfrm1 );
-
-/* Attempt to simplify the remapped Region. */
-         snewreg1 = astSimplify( newreg1 );
-
-/* Do the same for the second component Region. */
-         naxout2 = astGetNout( nmap2 );
-         newfrm2 = astPickAxes( cfrm, naxout2, axout2, NULL );
-         newreg2 = astMapRegion( reg2, nmap2, newfrm2 );
-         snewreg2 = astSimplify( newreg2 );
-
-/* If either component Region was simplified, create a new Prism from the
-   simplified Regions. */
-         if( snewreg1 != newreg1 || snewreg2 != newreg2 ) {
-            (void) astAnnul( new );
-            new = (AstRegion *) astPrism( snewreg1, snewreg2, "", status );
-
-/* Ensure the new Prism has the same Negated attribute as the original. */
-            if( neg ) astNegate( new );
-
-/* Ensure that the new Prism has the same axis order as the original
-   current Frame. */
-            perm = astMalloc( sizeof( int )*(size_t) ( naxout1 + naxout2 ) );
-            if( astOK ) {
-               for( i = 0; i < naxout1; i++ ) perm[ i ] = axout1[ i ];
-               for( ; i < naxout1 + naxout2; i++ ) perm[ i ] = axout2[ i - naxout1 ];
-               astPermAxes( new, perm );
-               perm = astFree( perm );
-            }
-         }
-
-/* Free resources. */
-         newfrm1 = astAnnul( newfrm1 );
-         newfrm2 = astAnnul( newfrm2 );
-         newreg1 = astAnnul( newreg1 );
-         newreg2 = astAnnul( newreg2 );
-         snewreg1 = astAnnul( snewreg1 );
-         snewreg2 = astAnnul( snewreg2 );
-      }
-
-/* Free resources. */
-      if( axout1 ) axout1 = astFree( axout1 );
-      if( axout2 ) axout2 = astFree( axout2 );
-      if( nmap1 ) nmap1 = astAnnul( nmap1 );
-      if( nmap2 ) nmap2 = astAnnul( nmap2 );
-   }
-
-/* If we have created a new Region, ensure any user-supplied uncertainty
-   that has been stored explicitly with the supplied Prism is passed on
-   to the new Region. */
-   if( new ) {
-      if( astTestUnc( reg ) ) {
-         unc = astGetUnc( reg, 0 );
-         astSetUnc( new, unc );
-      }
-
-/* Now invoke the parent Simplify method inherited from the Region class.
-   This will simplify the encapsulated FrameSet and uncertainty Region. */
-      result = (*parent_simplify)( (AstMapping *) new, status );
-      new = astAnnul( new );
-   }
-
-/* Free resources. */
-   reg1 = astAnnul( reg1 );
-   reg2 = astAnnul( reg2 );
-   cfrm = astAnnul( cfrm );
-   bcmap = astAnnul( bcmap );
-
-/* If any simplification could be performed, copy Region attributes from
-   the supplied Region to the returned Region, and return a pointer to it. */
-   if( result != this_mapping ) astRegOverlay( result, (AstRegion *) this_mapping, 0 );
-
-/* If an error occurred, annul the returned Mapping. */
-   if ( !astOK ) result = astAnnul( result );
-
-/* Return the result. */
-   return result;
-}
-
-static AstPointSet *Transform( AstMapping *this_mapping, AstPointSet *in,
-                               int forward, AstPointSet *out, int *status ) {
-/*
-*  Name:
-*     Transform
-
-*  Purpose:
-*     Apply a Prism to transform a set of points.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstPointSet *Transform( AstMapping *this, AstPointSet *in,
-*                             int forward, AstPointSet *out, int *status )
-
-*  Class Membership:
-*     Prism member function (over-rides the astTransform method inherited
-*     from the Region class).
-
-*  Description:
-*     This function takes a Prism and a set of points encapsulated in a
-*     PointSet and transforms the points so as to apply the required Region.
-*     This implies applying each of the Prism's component Regions in turn,
-*     either in series or in parallel.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism.
-*     in
-*        Pointer to the PointSet associated with the input coordinate values.
-*     forward
-*        A non-zero value indicates that the forward coordinate transformation
-*        should be applied, while a zero value requests the inverse
-*        transformation.
-*     out
-*        Pointer to a PointSet which will hold the transformed (output)
-*        coordinate values. A NULL value may also be given, in which case a
-*        new PointSet will be created by this function.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     Pointer to the output (possibly new) PointSet.
-
-*  Notes:
-*     -  A null pointer will be returned if this function is invoked with the
-*     global error status set, or if it should fail for any reason.
-*     -  The number of coordinate values per point in the input PointSet must
-*     match the number of coordinates for the Prism being applied.
-*     -  If an output PointSet is supplied, it must have space for sufficient
-*     number of points and coordinate values per point to accommodate the
-*     result. Any excess space will be ignored.
-*/
-
-/* Local Variables: */
-   AstCmpMap *map;               /* CmpMap containing component Regions */
-   AstPointSet *psb;             /* Pointer to base Frame PointSet */
-   AstPointSet *pset_tmp;        /* Pointer to PointSet holding base Frame positions*/
-   AstPointSet *result;          /* Pointer to output PointSet */
-   AstPrism *this;               /* Pointer to the Prism structure */
-   AstRegion *reg1;              /* Pointer to first component Region */
-   AstRegion *reg2;              /* Pointer to second component Region */
-   double **ptr_out;             /* Pointer to output coordinate data */
-   double **ptrb;                /* Pointer to base Frame axis values */
-   int coord;                    /* Zero-based index for coordinates */
-   int good;                     /* Is the point inside the Prism? */
-   int ncoord_out;               /* No. of coordinates per output point */
-   int ncoord_tmp;               /* No. of coordinates per base Frame point */
-   int neg;                      /* Has Prism been negated? */
-   int npoint;                   /* No. of points */
-   int point;                    /* Loop counter for points */
-
-/* Initialise. */
-   result = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return result;
-
-/* Get a Pointer to the Prism structure */
-   this = (AstPrism *) this_mapping;
-
-/* Get the component Regions, and the Negated value for the Prism. */
-   GetRegions( this, &reg1, &reg2, &neg, status );
-
-/* Apply the parent mapping using the stored pointer to the Transform member
-   function inherited from the parent Region class. This function validates
-   all arguments and generates an output PointSet if necessary, containing
-   a copy of the input PointSet. */
-   result = (*parent_transform)( this_mapping, in, forward, out, status );
-
-/* We will now extend the parent astTransform method by performing the
-   calculations needed to generate the output coordinate values. */
-
-/* First use the encapsulated FrameSet in the parent Region structure to
-   transform the supplied positions from the current Frame in the
-   encapsulated FrameSet (the Frame represented by the Prism), to the
-   base Frame (the Frame in which the component Regions are defined). Note,
-   the returned pointer may be a clone of the "in" pointer, and so we
-   must be carefull not to modify the contents of the returned PointSet. */
-   pset_tmp = astRegTransform( this, in, 0, NULL, NULL );
-
-/* Form a parallel CmpMap from the two component Regions. */
-   map = astCmpMap( reg1, reg2, 0, "", status );
-
-/* Apply the Mapping to the PointSet containing positions in the base Frame
-   of the parent Region structure (which is the same as the combination of
-   the current Frames of the component Regions). */
-   psb = astTransform( map, pset_tmp, 1, NULL );
-
-/* Annul the Mapping pointer. */
-   map = astAnnul( map );
-
-/* Determine the numbers of points and coordinates per point for these base
-   Frame PointSets and obtain pointers for accessing the base Frame and output
-   coordinate values. */
-   npoint = astGetNpoint( pset_tmp );
-   ncoord_tmp = astGetNcoord( pset_tmp );
-   ptrb = astGetPoints( psb );
-   ncoord_out = astGetNcoord( result );
-   ptr_out = astGetPoints( result );
-
-/* Perform coordinate arithmetic. */
-/* ------------------------------ */
-   if ( astOK ) {
-      for ( point = 0; point < npoint; point++ ) {
-         good = 1;
-
-         for ( coord = 0; coord < ncoord_tmp; coord++ ) {
-            if( ptrb[ coord ][ point ] == AST__BAD ){
-               good = 0;
-               break;
-            }
-         }
-
-         if( good == neg ) {
-            for ( coord = 0; coord < ncoord_out; coord++ ) {
-               ptr_out[ coord ][ point ] = AST__BAD;
-            }
-         }
-      }
-   }
-
-/* Free resources. */
-   reg1 = astAnnul( reg1 );
-   reg2 = astAnnul( reg2 );
-   psb = astAnnul( psb );
-   pset_tmp = astAnnul( pset_tmp );
-
-/* If an error occurred, clean up by deleting the output PointSet (if
-   allocated by this function) and setting a NULL result pointer. */
-   if ( !astOK ) {
-      if ( !out ) result = astDelete( result );
-      result = NULL;
-   }
-
-/* Return a pointer to the output PointSet. */
-   return result;
-}
-
-/* Copy constructor. */
-/* ----------------- */
-static void Copy( const AstObject *objin, AstObject *objout, int *status ) {
-/*
-*  Name:
-*     Copy
-
-*  Purpose:
-*     Copy constructor for Prism objects.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     void Copy( const AstObject *objin, AstObject *objout, int *status )
-
-*  Description:
-*     This function implements the copy constructor for Prism objects.
-
-*  Parameters:
-*     objin
-*        Pointer to the object to be copied.
-*     objout
-*        Pointer to the object being constructed.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     void
-
-*  Notes:
-*     -  This constructor makes a deep copy, including a copy of the component
-*     Regions within the Prism.
-*/
-
-/* Local Variables: */
-   AstPrism *in;                /* Pointer to input Prism */
-   AstPrism *out;               /* Pointer to output Prism */
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Obtain pointers to the input and output Prisms. */
-   in = (AstPrism *) objin;
-   out = (AstPrism *) objout;
-
-/* For safety, start by clearing any references to the input component
-   Regions from the output Prism. */
-   out->region1 = NULL;
-   out->region2 = NULL;
-
-/* Make copies of these Regions and store pointers to them in the output
-   Prism structure. */
-   out->region1 = astCopy( in->region1 );
-   out->region2 = astCopy( in->region2 );
-}
-
-/* Destructor. */
-/* ----------- */
-static void Delete( AstObject *obj, int *status ) {
-/*
-*  Name:
-*     Delete
-
-*  Purpose:
-*     Destructor for Prism objects.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     void Delete( AstObject *obj, int *status )
-
-*  Description:
-*     This function implements the destructor for Prism objects.
-
-*  Parameters:
-*     obj
-*        Pointer to the object to be deleted.
-*     status
-*        Pointer to the inherited status variable.
-
-*  Returned Value:
-*     void
-
-*  Notes:
-*     This function attempts to execute even if the global error status is
-*     set.
-*/
-
-/* Local Variables: */
-   AstPrism *this;              /* Pointer to Prism */
-
-/* Obtain a pointer to the Prism structure. */
-   this = (AstPrism *) obj;
-
-/* Annul the pointers to the component Regions. */
-   this->region1 = astAnnul( this->region1 );
-   this->region2 = astAnnul( this->region2 );
-}
-
-/* Dump function. */
-/* -------------- */
-static void Dump( AstObject *this_object, AstChannel *channel, int *status ) {
-/*
-*  Name:
-*     Dump
-
-*  Purpose:
-*     Dump function for Prism objects.
-
-*  Type:
-*     Private function.
-
-*  Synopsis:
-*     void Dump( AstObject *this, AstChannel *channel, int *status )
-
-*  Description:
-*     This function implements the Dump function which writes out data
-*     for the Prism class to an output Channel.
-
-*  Parameters:
-*     this
-*        Pointer to the Prism whose data are being written.
-*     channel
-*        Pointer to the Channel to which the data are being written.
-*     status
-*        Pointer to the inherited status variable.
-*/
-
-/* Local Variables: */
-   AstPrism *this;               /* Pointer to the Prism structure */
-
-/* Check the global error status. */
-   if ( !astOK ) return;
-
-/* Obtain a pointer to the Prism structure. */
-   this = (AstPrism *) this_object;
-
-/* Write out values representing the instance variables for the Prism
-   class.  Accompany these with appropriate comment strings, possibly
-   depending on the values being written.*/
-
-/* In the case of attributes, we first use the appropriate (private)
-   Test...  member function to see if they are set. If so, we then use
-   the (private) Get... function to obtain the value to be written
-   out.
-
-   For attributes which are not set, we use the astGet... method to
-   obtain the value instead. This will supply a default value
-   (possibly provided by a derived class which over-rides this method)
-   which is more useful to a human reader as it corresponds to the
-   actual default attribute value.  Since "set" will be zero, these
-   values are for information only and will not be read back. */
-
-/* First Region. */
-/* -------------- */
-   astWriteObject( channel, "RegionA", 1, 1, this->region1,
-                   "First component Region" );
-
-/* Second Region. */
-/* --------------- */
-   astWriteObject( channel, "RegionB", 1, 1, this->region2,
-                   "Second component Region" );
-}
-
-/* Standard class functions. */
-/* ========================= */
-/* Implement the astIsAPrism and astCheckPrism functions using the
-   macros defined for this purpose in the "object.h" header file. */
-astMAKE_ISA(Prism,Region)
-astMAKE_CHECK(Prism)
-
-AstPrism *astPrism_( void *region1_void, void *region2_void,
-                     const char *options, int *status, ...) {
-/*
-*+
-*  Name:
-*     astPrism
-
-*  Purpose:
-*     Create a Prism.
-
-*  Type:
-*     Protected function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstPrism *astPrism( AstRegion *region1, AstRegion *region2,
-*                         const char *options, ..., int *status )
-
-*  Class Membership:
-*     Prism constructor.
-
-*  Description:
-*     This function creates a new Prism and optionally initialises its
-*     attributes.
-
-*  Parameters:
-*     region1
-*        Pointer to the Region to be extruded.
-*     region2
-*        Pointer to the Region defining the extent of the extrusion.
-*     options
-*        Pointer to a null terminated string containing an optional
-*        comma-separated list of attribute assignments to be used for
-*        initialising the new Prism. The syntax used is the same as for the
-*        astSet method and may include "printf" format specifiers identified
-*        by "%" symbols in the normal way.
-*     status
-*        Pointer to the inherited status variable.
-*     ...
-*        If the "options" string contains "%" format specifiers, then an
-*        optional list of arguments may follow it in order to supply values to
-*        be substituted for these specifiers. The rules for supplying these
-*        are identical to those for the astSet method (and for the C "printf"
-*        function).
-
-*  Returned Value:
-*     A pointer to the new Prism.
-
-*  Notes:
-*     - A null pointer will be returned if this function is invoked
-*     with the global error status set, or if it should fail for any
-*     reason.
-*-
-
-*  Implementation Notes:
-*     - This function implements the basic Prism constructor which is
-*     available via the protected interface to the Prism class.  A
-*     public interface is provided by the astPrismId_ function.
-*     - Because this function has a variable argument list, it is
-*     invoked by a macro that evaluates to a function pointer (not a
-*     function invocation) and no checking or casting of arguments is
-*     performed before the function is invoked. Because of this, the
-*     "region1" and "region2" parameters are of type (void *) and are
-*     converted and validated within the function itself.
-*/
-
-/* Local Variables: */
-   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
-   AstPrism *new;                  /* Pointer to new Prism */
-   AstRegion *region1;             /* Pointer to first Region structure */
-   AstRegion *region2;             /* Pointer to second Region structure */
-   va_list args;                   /* Variable argument list */
-
-/* Initialise. */
-   new = NULL;
-
-/* Get a pointer to the thread specific global data structure. */
-   astGET_GLOBALS(NULL);
-
-/* Check the global status. */
-   if ( !astOK ) return new;
-
-/* Obtain and validate pointers to the Region structures provided. */
-   region1 = astCheckRegion( region1_void );
-   region2 = astCheckRegion( region2_void );
-   if ( astOK ) {
-
-/* Initialise the Prism, allocating memory and initialising the
-   virtual function table as well if necessary. */
-      new = astInitPrism( NULL, sizeof( AstPrism ), !class_init,
-                          &class_vtab, "Prism", region1, region2 );
-
-/* If successful, note that the virtual function table has been
-   initialised. */
-      if ( astOK ) {
-         class_init = 1;
-
-/* Obtain the variable argument list and pass it along with the
-   options string to the astVSet method to initialise the new Prism's
-   attributes. */
-         va_start( args, status );
-         astVSet( new, options, NULL, args );
-         va_end( args );
-
-/* If an error occurred, clean up by deleting the new object. */
-         if ( !astOK ) new = astDelete( new );
-      }
-   }
-
-/* Return a pointer to the new Prism. */
-   return new;
-}
-
-AstPrism *astPrismId_( void *region1_void, void *region2_void,
-                       const char *options, ... ) {
-/*
-*++
-*  Name:
-c     astPrism
-f     AST_PRISM
-
-*  Purpose:
-*     Create a Prism.
-
-*  Type:
-*     Public function.
-
-*  Synopsis:
-c     #include "prism.h"
-c     AstPrism *astPrism( AstRegion *region1, AstRegion *region2,
-c                         const char *options, ... )
-f     RESULT = AST_PRISM( REGION1, REGION2, OPTIONS, STATUS )
-
-*  Class Membership:
-*     Prism constructor.
-
-*  Description:
-*     This function creates a new Prism and optionally initialises
-*     its attributes.
-*
-*     A Prism is a Region which represents an extrusion of an existing Region
-*     into one or more orthogonal dimensions (specified by another Region).
-*     If the Region to be extruded has N axes, and the Region defining the
-*     extrusion has M axes, then the resulting Prism will have (M+N) axes.
-*     A point is inside the Prism if the first N axis values correspond to
-*     a point inside the Region being extruded, and the remaining M axis
-*     values correspond to a point inside the Region defining the extrusion.
-*
-*     As an example, a cylinder can be represented by extruding an existing
-*     Circle, using an Interval to define the extrusion. Ih this case, the
-*     Interval would have a single axis and would specify the upper and
-*     lower limits of the cylinder along its length.
-
-*  Parameters:
-c     region1
-f     REGION1 = INTEGER (Given)
-*        Pointer to the Region to be extruded.
-c     region2
-f     REGION2 = INTEGER (Given)
-*        Pointer to the Region defining the extent of the extrusion.
-c     options
-f     OPTIONS = CHARACTER * ( * ) (Given)
-c        Pointer to a null-terminated string containing an optional
-c        comma-separated list of attribute assignments to be used for
-c        initialising the new Prism. The syntax used is identical to
-c        that for the astSet function and may include "printf" format
-c        specifiers identified by "%" symbols in the normal way.
-f        A character string containing an optional comma-separated
-f        list of attribute assignments to be used for initialising the
-f        new Prism. The syntax used is identical to that for the
-f        AST_SET routine.
-c     ...
-c        If the "options" string contains "%" format specifiers, then
-c        an optional list of additional arguments may follow it in
-c        order to supply values to be substituted for these
-c        specifiers. The rules for supplying these are identical to
-c        those for the astSet function (and for the C "printf"
-c        function).
-f     STATUS = INTEGER (Given and Returned)
-f        The global status.
-
-*  Returned Value:
-c     astPrism()
-f     AST_PRISM = INTEGER
-*        A pointer to the new Prism.
-
-*  Notes:
-*     - Deep copies are taken of the supplied Regions. This means that
-*     any subsequent changes made to the component Regions using the
-*     supplied pointers will have no effect on the Prism.
-*     - A null Object pointer (AST__NULL) will be returned if this
-c     function is invoked with the AST error status set, or if it
-f     function is invoked with STATUS set to an error value, or if it
-*     should fail for any reason.
-*--
-
-*  Implementation Notes:
-*     - This function implements the external (public) interface to
-*     the astPrism constructor function. It returns an ID value
-*     (instead of a true C pointer) to external users, and must be
-*     provided because astPrism_ has a variable argument list which
-*     cannot be encapsulated in a macro (where this conversion would
-*     otherwise occur).
-*     - Because no checking or casting of arguments is performed
-*     before the function is invoked, the "region1" and "region2" parameters
-*     are of type (void *) and are converted from an ID value to a
-*     pointer and validated within the function itself.
-*     - The variable argument list also prevents this function from
-*     invoking astPrism_ directly, so it must be a re-implementation
-*     of it in all respects, except for the conversions between IDs
-*     and pointers on input/output of Objects.
-*/
-
-/* Local Variables: */
-   astDECLARE_GLOBALS              /* Pointer to thread-specific global data */
-   AstPrism *new;                  /* Pointer to new Prism */
-   AstRegion *region1;             /* Pointer to first Region structure */
-   AstRegion *region2;             /* Pointer to second Region structure */
-   int *status;                    /* Pointer to inherited status value */
-   va_list args;                   /* Variable argument list */
-
-/* Get a pointer to the thread specific global data structure. */
-   astGET_GLOBALS(NULL);
-
-/* Initialise. */
-   new = NULL;
-
-/* Get a pointer to the inherited status value. */
-   status = astGetStatusPtr;
-
-/* Check the global status. */
-   if ( !astOK ) return new;
-
-/* Obtain the Region pointers from the ID's supplied and validate the
-   pointers to ensure they identify valid Regions. */
-   region1 = astVerifyRegion( astMakePointer( region1_void ) );
-   region2 = astVerifyRegion( astMakePointer( region2_void ) );
-   if ( astOK ) {
-
-/* Initialise the Prism, allocating memory and initialising the
-   virtual function table as well if necessary. */
-      new = astInitPrism( NULL, sizeof( AstPrism ), !class_init,
-                          &class_vtab, "Prism", region1, region2 );
-
-/* If successful, note that the virtual function table has been initialised. */
-      if ( astOK ) {
-         class_init = 1;
-
-/* Obtain the variable argument list and pass it along with the
-   options string to the astVSet method to initialise the new Prism's
-   attributes. */
-         va_start( args, options );
-         astVSet( new, options, NULL, args );
-         va_end( args );
-
-/* If an error occurred, clean up by deleting the new object. */
-         if ( !astOK ) new = astDelete( new );
-      }
-   }
-
-/* Return an ID value for the new Prism. */
-   return astMakeId( new );
-}
-
-AstPrism *astInitPrism_( void *mem, size_t size, int init, AstPrismVtab *vtab,
-                         const char *name, AstRegion *region1,
-                         AstRegion *region2, int *status ) {
-/*
-*+
-*  Name:
-*     astInitPrism
-
-*  Purpose:
-*     Initialise a Prism.
-
-*  Type:
-*     Protected function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstPrism *astInitPrism_( void *mem, size_t size, int init,
-*                              AstPrismVtab *vtab, const char *name,
-*                              AstRegion *region1, AstRegion *region2 )
-
-*  Class Membership:
-*     Prism initialiser.
-
-*  Description:
-*     This function is provided for use by class implementations to initialise
-*     a new Prism object. It allocates memory (if necessary) to
-*     accommodate the Prism plus any additional data associated with the
-*     derived class. It then initialises a Prism structure at the start
-*     of this memory. If the "init" flag is set, it also initialises the
-*     contents of a virtual function table for a Prism at the start of
-*     the memory passed via the "vtab" parameter.
-
-*  Parameters:
-*     mem
-*        A pointer to the memory in which the Prism is to be initialised.
-*        This must be of sufficient size to accommodate the Prism data
-*        (sizeof(Prism)) plus any data used by the derived class. If a
-*        value of NULL is given, this function will allocate the memory itself
-*        using the "size" parameter to determine its size.
-*     size
-*        The amount of memory used by the Prism (plus derived class
-*        data). This will be used to allocate memory if a value of NULL is
-*        given for the "mem" parameter. This value is also stored in the
-*        Prism structure, so a valid value must be supplied even if not
-*        required for allocating memory.
-*     init
-*        A logical flag indicating if the Prism's virtual function table
-*        is to be initialised. If this value is non-zero, the virtual function
-*        table will be initialised by this function.
-*     vtab
-*        Pointer to the start of the virtual function table to be associated
-*        with the new Prism.
-*     name
-*        Pointer to a constant null-terminated character string which contains
-*        the name of the class to which the new object belongs (it is this
-*        pointer value that will subsequently be returned by the Object
-*        astClass function).
-*     region1
-*        Pointer to the first Region.
-*     region2
-*        Pointer to the second Region.
-
-*  Returned Value:
-*     A pointer to the new Prism.
-
-*  Notes:
-*     -  A null pointer will be returned if this function is invoked with the
-*     global error status set, or if it should fail for any reason.
-*-
-*/
-
-/* Local Variables: */
-   AstPrism *new;                /* Pointer to new Prism */
-   AstFrame *frm1;               /* Frame encapsulated by 1st Region */
-   AstFrame *frm2;               /* Frame encapsulated by 2nd Region */
-   AstFrame *frm;                /* CmpFrame formed from frm1 and frm2 */
-   AstMapping *map;              /* Mapping between two supplied Regions */
-   AstRegion *reg1;              /* Copy of first supplied Region */
-   AstRegion *reg2;              /* Copy of second supplied Region */
-
-/* Check the global status. */
-   if ( !astOK ) return NULL;
-
-/* If necessary, initialise the virtual function table. */
-   if ( init ) astInitPrismVtab( vtab, name );
-
-/* Initialise. */
-   new = NULL;
-   reg2 = NULL;
-
-/* Take a copy of the two supplied Regions. */
-   reg1 = astCopy( region1 );
-   reg2 = astCopy( region2 );
-
-/* Form a CmpFrame representing the combined Frame of these two Regions. */
-   frm1 = astRegFrame( reg1 );
-   frm2 = astRegFrame( reg2 );
-   frm = (AstFrame *) astCmpFrame( frm1, frm2, "", status );
-
-/* Initialise a Region structure (the parent class) as the first component
-   within the Prism structure, allocating memory if necessary. A NULL
-   PointSet is suppled as the two component Regions will perform the function
-   of defining the Region shape. The base Frame of the FrameSet in the
-   parent Region structure will be the CmpFrame formed from the two component
-   Regions. */
-   if ( astOK ) {
-      new = (AstPrism *) astInitRegion( mem, size, 0, (AstRegionVtab *) vtab,
-                                        name, frm, NULL, NULL );
-
-/* Initialise the Prism data. */
-/* --------------------------- */
-/* Store pointers to the component Regions. */
-      new->region1 = reg1;
-      new->region2 = reg2;
-
-/* If the base->current Mapping in the FrameSet within a component Region
-   is a UnitMap, then the FrameSet does not need to be included in the
-   Dump of the new Prism. Set the RegionFS attribute of the component
-   Region to zero to flag this. */
-      map = astGetMapping( reg1->frameset, AST__BASE, AST__CURRENT );
-      if( astIsAUnitMap( map ) ) astSetRegionFS( reg1, 0 );
-      map = astAnnul( map );
-
-      map = astGetMapping( reg2->frameset, AST__BASE, AST__CURRENT );
-      if( astIsAUnitMap( map ) ) astSetRegionFS( reg2, 0 );
-      map = astAnnul( map );
-
-/* If an error occurred, clean up by annulling the Region pointers and
-   deleting the new object. */
-      if ( !astOK ) {
-         new->region1 = astAnnul( new->region1 );
-         new->region2 = astAnnul( new->region2 );
-         new = astDelete( new );
-      }
-   }
-
-/* Free resources */
-   frm = astAnnul( frm );
-   frm1 = astAnnul( frm1 );
-   frm2 = astAnnul( frm2 );
-
-/* Return a pointer to the new object. */
-   return new;
-}
-
-AstPrism *astLoadPrism_( void *mem, size_t size, AstPrismVtab *vtab,
-                         const char *name, AstChannel *channel, int *status ) {
-/*
-*+
-*  Name:
-*     astLoadPrism
-
-*  Purpose:
-*     Load a Prism.
-
-*  Type:
-*     Protected function.
-
-*  Synopsis:
-*     #include "prism.h"
-*     AstPrism *astLoadPrism( void *mem, size_t size, AstPrismVtab *vtab,
-*                             const char *name, AstChannel *channel )
-
-*  Class Membership:
-*     Prism loader.
-
-*  Description:
-*     This function is provided to load a new Prism using data read
-*     from a Channel. It first loads the data used by the parent class
-*     (which allocates memory if necessary) and then initialises a
-*     Prism structure in this memory, using data read from the input
-*     Channel.
-*
-*     If the "init" flag is set, it also initialises the contents of a
-*     virtual function table for a Prism at the start of the memory
-*     passed via the "vtab" parameter.
-
-
-*  Parameters:
-*     mem
-*        A pointer to the memory into which the Prism is to be
-*        loaded.  This must be of sufficient size to accommodate the
-*        Prism data (sizeof(Prism)) plus any data used by derived
-*        classes. If a value of NULL is given, this function will
-*        allocate the memory itself using the "size" parameter to
-*        determine its size.
-*     size
-*        The amount of memory used by the Prism (plus derived class
-*        data).  This will be used to allocate memory if a value of
-*        NULL is given for the "mem" parameter. This value is also
-*        stored in the Prism structure, so a valid value must be
-*        supplied even if not required for allocating memory.
-*
-*        If the "vtab" parameter is NULL, the "size" value is ignored
-*        and sizeof(AstPrism) is used instead.
-*     vtab
-*        Pointer to the start of the virtual function table to be
-*        associated with the new Prism. If this is NULL, a pointer to
-*        the (static) virtual function table for the Prism class is
-*        used instead.
-*     name
-*        Pointer to a constant null-terminated character string which
-*        contains the name of the class to which the new object
-*        belongs (it is this pointer value that will subsequently be
-*        returned by the astGetClass method).
-*
-*        If the "vtab" parameter is NULL, the "name" value is ignored
-*        and a pointer to the string "Prism" is used instead.
-
-*  Returned Value:
-*     A pointer to the new Prism.
-
-*  Notes:
-*     - A null pointer will be returned if this function is invoked
-*     with the global error status set, or if it should fail for any
-*     reason.
-*-
-*/
-
-/* Local Variables: */
-   astDECLARE_GLOBALS      /* Pointer to thread-specific global data */
-   AstFrame *cfrm;         /* Frame containing required axes */
-   AstFrame *f1;           /* Base Frame in parent Region */
-   AstPrism *new;          /* Pointer to the new Prism */
-   AstRegion *creg;        /* Pointer to component Region */
-   int *axes;              /* Pointer to array of axis indices */
-   int i;                  /* Loop count */
-   int nax1;               /* No.of axes in 1st component Frame */
-   int nax2;               /* No.of axes in 2nd component Frame */
-
-/* Initialise. */
-   new = NULL;
-
-/* Check the global error status. */
-   if ( !astOK ) return new;
-
-/* Get a pointer to the thread specific global data structure. */
-   astGET_GLOBALS(channel);
-
-/* If a NULL virtual function table has been supplied, then this is
-   the first loader to be invoked for this Prism. In this case the
-   Prism belongs to this class, so supply appropriate values to be
-   passed to the parent class loader (and its parent, etc.). */
-   if ( !vtab ) {
-      size = sizeof( AstPrism );
-      vtab = &class_vtab;
-      name = "Prism";
-
-/* If required, initialise the virtual function table for this class. */
-      if ( !class_init ) {
-         astInitPrismVtab( vtab, name );
-         class_init = 1;
-      }
-   }
-
-/* Invoke the parent class loader to load data for all the ancestral
-   classes of the current one, returning a pointer to the resulting
-   partly-built Prism. */
-   new = astLoadRegion( mem, size, (AstRegionVtab *) vtab, name,
-                         channel );
-
-   if ( astOK ) {
-
-/* Read input data. */
-/* ================ */
-/* Request the input Channel to read all the input data appropriate to
-   this class into the internal "values list". */
-      astReadClassData( channel, "Prism" );
-
-/* Now read each individual data item from this list and use it to
-   initialise the appropriate instance variable(s) for this class. */
-
-/* In the case of attributes, we first read the "raw" input value,
-   supplying the "unset" value as the default. If a "set" value is
-   obtained, we then use the appropriate (private) Set... member
-   function to validate and set the value properly. */
-
-/* First Region. */
-/* -------------- */
-      new->region1 = astReadObject( channel, "regiona", NULL );
-
-/* Second Region. */
-/* --------------- */
-      new->region2 = astReadObject( channel, "regionb", NULL );
-
-/* Either component Region may currently contain a dummy FrameSet rather than
-   the correct FrameSet (see the Dump function for this class). In this case,
-   the correct FrameSet will have copies of selected axes from the base Frame
-   of the new Prism as both its current and base Frames, and these are
-   connected by a UnitMap (this is equivalent to a FrameSet containing a
-   single Frame). However if the new Prism being loaded has itself got a dummy
-   FrameSet, then we do not do this since we do not yet know what the correct
-   FrameSet is. In this case we wait until the parent Region invokes the
-   astSetRegFS method on the new Prism. */
-      if( !astRegDummyFS( new ) ) {
-         f1 = astGetFrame( ((AstRegion *) new)->frameset, AST__BASE );
-
-         creg = new->region1;
-         nax1 = astGetNaxes( creg );
-         if( astRegDummyFS( creg ) ) {
-            axes = astMalloc( sizeof( int )*(size_t) nax1 );
-            if( astOK ) for( i = 0; i < nax1; i++ ) axes[ i ] = i;
-            cfrm = astPickAxes( f1, nax1, axes, NULL );
-            astSetRegFS( creg, cfrm );
-            axes = astFree( axes );
-            cfrm = astAnnul( cfrm );
-         }
-
-         creg = new->region2;
-         if( astRegDummyFS( creg ) ) {
-            nax2 = astGetNaxes( creg );
-            axes = astMalloc( sizeof( int )*(size_t) nax2 );
-            if( astOK ) for( i = 0; i < nax2; i++ ) axes[ i ] = nax1 + i;
-            cfrm = astPickAxes( f1, nax2, axes, NULL );
-            astSetRegFS( creg, cfrm );
-            axes = astFree( axes );
-            cfrm = astAnnul( cfrm );
-         }
-
-         f1 = astAnnul( f1 );
-      }
-
-/* If an error occurred, clean up by deleting the new Prism. */
-      if ( !astOK ) new = astDelete( new );
-   }
-
-/* Return the new Prism pointer. */
-   return new;
-}
-
-/* Virtual function interfaces. */
-/* ============================ */
-/* These provide the external interface to the virtual functions defined by
-   this class. Each simply checks the global error status and then locates and
-   executes the appropriate member function, using the function pointer stored
-   in the object's virtual function table (this pointer is located using the
-   astMEMBER macro defined in "object.h").
-
-   Note that the member function may not be the one defined here, as it may
-   have been over-ridden by a derived class. However, it should still have the
-   same interface. */
-
-/* None. */
-
-
-