Merge commit '7fde2daeed593684120d75de07598154f3ddaf2c' as 'ast'

1 files changed, 2074 insertions, 0 deletions

diff --git a/ast/zoommap.c b/ast/zoommap.c
new file mode 100644
index 0000000..44177d1
--- /dev/null
+++ b/ast/zoommap.c
@@ -0,0 +1,2074 @@
+/*
+*class++
+*  Name:
+*     ZoomMap
+
+*  Purpose:
+*     Zoom coordinates about the origin.
+
+*  Constructor Function:
+c     astZoomMap
+f     AST_ZOOMMAP
+
+*  Description:
+*     The ZoomMap class implements a Mapping which performs a "zoom"
+*     transformation by multiplying all coordinate values by the same
+*     scale factor (the inverse transformation is performed by
+*     dividing by this scale factor). The number of coordinate values
+*     representing each point is unchanged.
+
+*  Inheritance:
+*     The ZoomMap class inherits from the Mapping class.
+
+*  Attributes:
+*     In addition to those attributes common to all Mappings, every
+*     ZoomMap also has the following attributes:
+*
+*     - Zoom: ZoomMap scale factor
+
+*  Functions:
+c     The ZoomMap class does not define any new functions beyond those
+f     The ZoomMap class does not define any new routines beyond those
+*     which are applicable to all Mappings.
+
+*  Copyright:
+*     Copyright (C) 1997-2006 Council for the Central Laboratory of the
+*     Research Councils
+
+*  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:
+*     RFWS: R.F. Warren-Smith (Starlink)
+*     DSB: David S. Berry (Starlink)
+
+*  History:
+*     1-FEB-1996 (RFWS):
+*        Original version.
+*     18-JUL-1996 (RFWS):
+*        Updated to support attributes and an external interface.
+*     10-SEP-1996 (RFWS):
+*        Added I/O facilities.
+*     4-JUN-1997 (RFWS):
+*        Over-ride the MapMerge method to provide ZoomMap
+*        simplification facilities.
+*     8-JAN-2003 (DSB):
+*        Changed private InitVtab method to protected astInitZoomMapVtab
+*        method.
+*     10-MAY-2006 (DSB):
+*        Override astEqual.
+*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 ZoomMap
+
+/* 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 "globals.h"             /* Thread-safe global data access */
+#include "object.h"              /* Base Object class */
+#include "pointset.h"            /* Sets of points/coordinates */
+#include "mapping.h"             /* Coordinate mappings (parent class) */
+#include "channel.h"             /* I/O channels */
+#include "unitmap.h"             /* Unit Mappings */
+#include "matrixmap.h"           /* Matrix Mappings */
+#include "zoommap.h"             /* Interface definition for this class */
+
+/* Error code definitions. */
+/* ----------------------- */
+#include "ast_err.h"             /* AST error codes */
+
+/* C header files. */
+/* --------------- */
+#include <float.h>
+#include <math.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.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 AstPointSet *(* parent_transform)( AstMapping *, AstPointSet *, int, AstPointSet *, int * );
+static const char *(* parent_getattrib)( AstObject *, const char *, int * );
+static int (* parent_testattrib)( AstObject *, const char *, int * );
+static void (* parent_clearattrib)( AstObject *, const char *, int * );
+static void (* parent_setattrib)( AstObject *, const char *, int * );
+
+/* Define macros for accessing each item of thread specific global data. */
+#ifdef THREAD_SAFE
+
+/* Define how to initialise thread-specific globals. */
+#define GLOBAL_inits \
+   globals->Class_Init = 0; \
+   globals->GetAttrib_Buff[ 0 ] = 0;
+
+/* Create the function that initialises global data for this module. */
+astMAKE_INITGLOBALS(ZoomMap)
+
+/* Define macros for accessing each item of thread specific global data. */
+#define class_init astGLOBAL(ZoomMap,Class_Init)
+#define class_vtab astGLOBAL(ZoomMap,Class_Vtab)
+#define getattrib_buff astGLOBAL(ZoomMap,GetAttrib_Buff)
+
+
+
+/* If thread safety is not needed, declare and initialise globals at static
+   variables. */
+#else
+
+static char getattrib_buff[ 101 ];
+
+
+/* Define the class virtual function table and its initialisation flag
+   as static variables. */
+static AstZoomMapVtab 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. */
+AstZoomMap *astZoomMapId_( int, double, const char *, ... );
+
+/* Prototypes for Private Member Functions. */
+/* ======================================== */
+static AstPointSet *Transform( AstMapping *, AstPointSet *, int, AstPointSet *, int * );
+static const char *GetAttrib( AstObject *, const char *, int * );static double GetZoom( AstZoomMap *, int * );
+static double Rate( AstMapping *, double *, int, int, int * );
+static int *MapSplit( AstMapping *, int, const int *, AstMapping **, int * );
+static int Equal( AstObject *, AstObject *, int * );
+static int GetIsLinear( AstMapping *, int * );
+static int MapMerge( AstMapping *, int, int, int *, AstMapping ***, int **, int * );
+static int TestAttrib( AstObject *, const char *, int * );
+static int TestZoom( AstZoomMap *, int * );
+static void ClearAttrib( AstObject *, const char *, int * );
+static void ClearZoom( AstZoomMap *, int * );
+static void Dump( AstObject *, AstChannel *, int * );
+static void SetAttrib( AstObject *, const char *, int * );
+static void SetZoom( AstZoomMap *, double, int * );
+
+/* Member functions. */
+/* ================= */
+static void ClearAttrib( AstObject *this_object, const char *attrib, int *status ) {
+/*
+*  Name:
+*     ClearAttrib
+
+*  Purpose:
+*     Clear an attribute value for a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     void ClearAttrib( AstObject *this, const char *attrib, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the astClearAttrib protected
+*     method inherited from the Mapping class).
+
+*  Description:
+*     This function clears the value of a specified attribute for a
+*     ZoomMap, so that the default value will subsequently be used.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap.
+*     attrib
+*        Pointer to a null-terminated string specifying the attribute
+*        name.  This should be in lower case with no surrounding white
+*        space.
+*     status
+*        Pointer to the inherited status variable.
+*/
+
+/* Local Variables: */
+   AstZoomMap *this;             /* Pointer to the ZoomMap structure */
+
+/* Check the global error status. */
+   if ( !astOK ) return;
+
+/* Obtain a pointer to the ZoomMap structure. */
+   this = (AstZoomMap *) this_object;
+
+/* Check the attribute name and clear the appropriate attribute. */
+
+/* Zoom. */
+/* ----- */
+   if ( !strcmp( attrib, "zoom" ) ) {
+      astClearZoom( this );
+
+/* If the attribute is still not recognised, pass it on to the parent
+   method for further interpretation. */
+   } else {
+      (*parent_clearattrib)( this_object, attrib, status );
+   }
+}
+
+static int Equal( AstObject *this_object, AstObject *that_object, int *status ) {
+/*
+*  Name:
+*     Equal
+
+*  Purpose:
+*     Test if two ZoomMaps are equivalent.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     int Equal( AstObject *this, AstObject *that, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the astEqual protected
+*     method inherited from the astMapping class).
+
+*  Description:
+*     This function returns a boolean result (0 or 1) to indicate whether
+*     two ZoomMaps are equivalent.
+
+*  Parameters:
+*     this
+*        Pointer to the first Object (a ZoomMap).
+*     that
+*        Pointer to the second Object.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     One if the ZoomMaps are equivalent, zero otherwise.
+
+*  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: */
+   AstZoomMap *that;
+   AstZoomMap *this;
+   int nin;
+   int nout;
+   int result;
+
+/* Initialise. */
+   result = 0;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Obtain pointers to the two ZoomMap structures. */
+   this = (AstZoomMap *) this_object;
+   that = (AstZoomMap *) that_object;
+
+/* Check the second object is a ZoomMap. We know the first is a
+   ZoomMap since we have arrived at this implementation of the virtual
+   function. */
+   if( astIsAZoomMap( that ) ) {
+
+/* Get the number of inputs and outputs and check they are the same for both. */
+      nin = astGetNin( this );
+      nout = astGetNout( this );
+      if( astGetNin( that ) == nin && astGetNout( that ) == nout ) {
+
+/* If the Invert flags for the two ZoomMaps differ, it may still be possible
+   for them to be equivalent. First compare the ZoomMaps if their Invert
+   flags are the same. In this case all the attributes of the two ZoomMaps
+   must be identical. */
+         if( astGetInvert( this ) == astGetInvert( that ) ) {
+            result = ( astEQUAL( this->zoom, that->zoom ) );
+
+/* If the Invert flags for the two ZoomMaps differ, the attributes of the two
+   ZoomMaps must be inversely related to each other. */
+         } else {
+            result = ( astEQUAL( this->zoom, 1.0/that->zoom ) );
+
+         }
+      }
+   }
+
+/* If an error occurred, clear the result value. */
+   if ( !astOK ) result = 0;
+
+/* Return the result, */
+   return result;
+}
+
+static const char *GetAttrib( AstObject *this_object, const char *attrib, int *status ) {
+/*
+*  Name:
+*     GetAttrib
+
+*  Purpose:
+*     Get the value of a specified attribute for a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     const char *GetAttrib( AstObject *this, const char *attrib, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the protected astGetAttrib
+*     method inherited from the Mapping class).
+
+*  Description:
+*     This function returns a pointer to the value of a specified
+*     attribute for a ZoomMap, formatted as a character string.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap.
+*     attrib
+*        Pointer to a null-terminated string containing the name of
+*        the attribute whose value is required. This name should be in
+*        lower case, with all white space removed.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     - Pointer to a null-terminated string containing the attribute
+*     value.
+
+*  Notes:
+*     - The returned string pointer may point at memory allocated
+*     within the ZoomMap, or at static memory. The contents of the
+*     string may be over-written or the pointer may become invalid
+*     following a further invocation of the same function or any
+*     modification of the ZoomMap. A copy of the string should
+*     therefore be made if necessary.
+*     - 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 */
+   AstZoomMap *this;             /* Pointer to the ZoomMap structure */
+   const char *result;           /* Pointer value to return */
+   double zoom;                  /* Zoom attribute value */
+
+/* Initialise. */
+   result = NULL;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Get a pointer to the thread specific global data structure. */
+   astGET_GLOBALS(this_object);
+
+/* Obtain a pointer to the ZoomMap structure. */
+   this = (AstZoomMap *) this_object;
+
+/* Compare "attrib" with each recognised attribute name in turn,
+   obtaining the value of the required attribute. If necessary, write
+   the value into "getattrib_buff" as a null-terminated string in an appropriate
+   format.  Set "result" to point at the result string. */
+
+/* Zoom. */
+/* ----- */
+   if ( !strcmp( attrib, "zoom" ) ) {
+      zoom = astGetZoom( this );
+      if ( astOK ) {
+         (void) sprintf( getattrib_buff, "%.*g", DBL_DIG, zoom );
+         result = getattrib_buff;
+      }
+
+/* If the attribute name was not recognised, pass it on to the parent
+   method for further interpretation. */
+   } else {
+      result = (*parent_getattrib)( this_object, attrib, status );
+   }
+
+/* Return the result. */
+   return result;
+}
+
+static int GetIsLinear( AstMapping *this_mapping, int *status ){
+/*
+*  Name:
+*     GetIsLinear
+
+*  Purpose:
+*     Return the value of the IsLinear attribute for a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "mapping.h"
+*     void GetIsLinear( AstMapping *this, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the protected astGetIsLinear
+*     method inherited from the Mapping class).
+
+*  Description:
+*     This function returns the value of the IsLinear attribute for a
+*     Frame, which is always one.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap.
+*     status
+*        Pointer to the inherited status variable.
+*/
+   return 1;
+}
+
+void astInitZoomMapVtab_(  AstZoomMapVtab *vtab, const char *name, int *status ) {
+/*
+*+
+*  Name:
+*     astInitZoomMapVtab
+
+*  Purpose:
+*     Initialise a virtual function table for a ZoomMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     void astInitZoomMapVtab( AstZoomMapVtab *vtab, const char *name )
+
+*  Class Membership:
+*     ZoomMap vtab initialiser.
+
+*  Description:
+*     This function initialises the component of a virtual function
+*     table which is used by the ZoomMap 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 */
+   AstObjectVtab *object;        /* Pointer to Object component of Vtab */
+   AstMappingVtab *mapping;      /* Pointer to Mapping 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. */
+   astInitMappingVtab( (AstMappingVtab *) vtab, name );
+
+/* Store a unique "magic" value in the virtual function table. This
+   will be used (by astIsAZoomMap) 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 = &(((AstMappingVtab *) vtab)->id);
+
+/* Initialise member function pointers. */
+/* ------------------------------------ */
+/* Store pointers to the member functions (implemented here) that provide
+   virtual methods for this class. */
+   vtab->ClearZoom = ClearZoom;
+   vtab->GetZoom = GetZoom;
+   vtab->SetZoom = SetZoom;
+   vtab->TestZoom = TestZoom;
+
+/* 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;
+
+   parent_clearattrib = object->ClearAttrib;
+   object->ClearAttrib = ClearAttrib;
+   parent_getattrib = object->GetAttrib;
+   object->GetAttrib = GetAttrib;
+   parent_setattrib = object->SetAttrib;
+   object->SetAttrib = SetAttrib;
+   parent_testattrib = object->TestAttrib;
+   object->TestAttrib = TestAttrib;
+
+   parent_transform = mapping->Transform;
+   mapping->Transform = Transform;
+
+/* Store replacement pointers for methods which will be over-ridden by
+   new member functions implemented here. */
+   object->Equal = Equal;
+   mapping->MapMerge = MapMerge;
+   mapping->MapSplit = MapSplit;
+   mapping->Rate = Rate;
+   mapping->GetIsLinear = GetIsLinear;
+
+/* Declare the class dump function. There is no copy constructor or
+   destructor. */
+   astSetDump( vtab, Dump, "ZoomMap", "Zoom about the origin" );
+
+/* 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) );
+   }
+}
+
+static int MapMerge( AstMapping *this, int where, int series, int *nmap,
+                     AstMapping ***map_list, int **invert_list, int *status ) {
+/*
+*  Name:
+*     MapMerge
+
+*  Purpose:
+*     Simplify a sequence of Mappings containing a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "mapping.h"
+*     int MapMerge( AstMapping *this, int where, int series, int *nmap,
+*                   AstMapping ***map_list, int **invert_list, int *status )
+
+*  Class Membership:
+*     ZoomMap method (over-rides the protected astMapMerge method
+*     inherited from the Mapping class).
+
+*  Description:
+*     This function attempts to simplify a sequence of Mappings by
+*     merging a nominated ZoomMap in the sequence with its neighbours,
+*     so as to shorten the sequence if possible.
+*
+*     In many cases, simplification will not be possible and the
+*     function will return -1 to indicate this, without further
+*     action.
+*
+*     In most cases of interest, however, this function will either
+*     attempt to replace the nominated ZoomMap with one which it
+*     considers simpler, or to merge it with the Mappings which
+*     immediately precede it or follow it in the sequence (both will
+*     normally be considered). This is sufficient to ensure the
+*     eventual simplification of most Mapping sequences by repeated
+*     application of this function.
+*
+*     In some cases, the function may attempt more elaborate
+*     simplification, involving any number of other Mappings in the
+*     sequence. It is not restricted in the type or scope of
+*     simplification it may perform, but will normally only attempt
+*     elaborate simplification in cases where a more straightforward
+*     approach is not adequate.
+
+*  Parameters:
+*     this
+*        Pointer to the nominated ZoomMap which is to be merged with
+*        its neighbours. This should be a cloned copy of the ZoomMap
+*        pointer contained in the array element "(*map_list)[where]"
+*        (see below). This pointer will not be annulled, and the
+*        ZoomMap it identifies will not be modified by this function.
+*     where
+*        Index in the "*map_list" array (below) at which the pointer
+*        to the nominated ZoomMap resides.
+*     series
+*        A non-zero value indicates that the sequence of Mappings to
+*        be simplified will be applied in series (i.e. one after the
+*        other), whereas a zero value indicates that they will be
+*        applied in parallel (i.e. on successive sub-sets of the
+*        input/output coordinates).
+*     nmap
+*        Address of an int which counts the number of Mappings in the
+*        sequence. On entry this should be set to the initial number
+*        of Mappings. On exit it will be updated to record the number
+*        of Mappings remaining after simplification.
+*     map_list
+*        Address of a pointer to a dynamically allocated array of
+*        Mapping pointers (produced, for example, by the astMapList
+*        method) which identifies the sequence of Mappings. On entry,
+*        the initial sequence of Mappings to be simplified should be
+*        supplied.
+*
+*        On exit, the contents of this array will be modified to
+*        reflect any simplification carried out. Any form of
+*        simplification may be performed. This may involve any of: (a)
+*        removing Mappings by annulling any of the pointers supplied,
+*        (b) replacing them with pointers to new Mappings, (c)
+*        inserting additional Mappings and (d) changing their order.
+*
+*        The intention is to reduce the number of Mappings in the
+*        sequence, if possible, and any reduction will be reflected in
+*        the value of "*nmap" returned. However, simplifications which
+*        do not reduce the length of the sequence (but improve its
+*        execution time, for example) may also be performed, and the
+*        sequence might conceivably increase in length (but normally
+*        only in order to split up a Mapping into pieces that can be
+*        more easily merged with their neighbours on subsequent
+*        invocations of this function).
+*
+*        If Mappings are removed from the sequence, any gaps that
+*        remain will be closed up, by moving subsequent Mapping
+*        pointers along in the array, so that vacated elements occur
+*        at the end. If the sequence increases in length, the array
+*        will be extended (and its pointer updated) if necessary to
+*        accommodate any new elements.
+*
+*        Note that any (or all) of the Mapping pointers supplied in
+*        this array may be annulled by this function, but the Mappings
+*        to which they refer are not modified in any way (although
+*        they may, of course, be deleted if the annulled pointer is
+*        the final one).
+*     invert_list
+*        Address of a pointer to a dynamically allocated array which,
+*        on entry, should contain values to be assigned to the Invert
+*        attributes of the Mappings identified in the "*map_list"
+*        array before they are applied (this array might have been
+*        produced, for example, by the astMapList method). These
+*        values will be used by this function instead of the actual
+*        Invert attributes of the Mappings supplied, which are
+*        ignored.
+*
+*        On exit, the contents of this array will be updated to
+*        correspond with the possibly modified contents of the
+*        "*map_list" array.  If the Mapping sequence increases in
+*        length, the "*invert_list" array will be extended (and its
+*        pointer updated) if necessary to accommodate any new
+*        elements.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     If simplification was possible, the function returns the index
+*     in the "map_list" array of the first element which was
+*     modified. Otherwise, it returns -1 (and makes no changes to the
+*     arrays supplied).
+
+*  Notes:
+*     - A value of -1 will be returned if this function is invoked
+*     with the global error status set, or if it should fail for any
+*     reason.
+*/
+
+/* Local Variables: */
+   AstMapping *map;              /* Pointer to Mapping */
+   AstMapping *new;              /* Pointer to replacement Mapping */
+   const char *class;            /* Pointer to Mapping class string */
+   double *zooms;                /* Pointer to zoom factor array */
+   double maxzoom;               /* Maximum zoom factor */
+   double minzoom;               /* Minimum zoom factor */
+   double zoom;                  /* Zoom factor */
+   int coord;                    /* Loop counter for coordinates */
+   int imap1;                    /* Index of first ZoomMap */
+   int imap2;                    /* Index of last ZoomMap */
+   int imap;                     /* Loop counter for Mappings */
+   int ncoord;                   /* Number of input/output coordinates */
+   int ngone;                    /* Number of Mappings eliminated */
+   int nin;                      /* Total number of input coordinates */
+   int nzoom;                    /* Number of zoom factors */
+   int result;                   /* Result value to return */
+   int simpler;                  /* Mapping(s) simplified? */
+   int single;                   /* Replacement is a single ZoomMap? */
+   int unit;                     /* Replacement Mapping is a UnitMap? */
+
+/* Initialise the returned result. */
+   result = -1;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Further initialisation. */
+   new = NULL;
+   ngone = 0;
+   simpler = 0;
+
+/* In series. */
+/* ---------- */
+/* Handle the case where the Mappings are connected in series. */
+   if ( series ) {
+
+/* Obtain the effective zoom factor of the nominated Mapping (which is
+   a ZoomMap) when its Invert attribute is set to the value given. */
+      zoom = astGetZoom( ( *map_list )[ where ] );
+      if ( ( *invert_list )[ where ] ) zoom = 1.0 / zoom;
+
+/* Search adjacent lower-numbered Mappings and identify the class to
+   which they belong. */
+      imap1 = where;
+      while ( astOK && ( ( imap1 - 1 ) >= 0 ) ) {
+         map = ( *map_list )[ imap1 - 1 ];
+         class = astGetClass( map );
+         if ( astOK ) {
+
+/* For each ZoomMap found, obtain the effective zoom factor (taking
+   account of the associated invert flag value), and accumulate the
+   overall zoom factor to be used for the simplified Mapping. */
+            if ( !strcmp( class, "ZoomMap" ) ) {
+               if ( ( *invert_list )[ imap1 - 1 ] ) {
+                  zoom /= astGetZoom( map );
+               } else {
+                  zoom *= astGetZoom( map );
+               }
+
+/* UnitMaps have an effective zoom factor of unity, so we include them
+   but they so have no effect. Quit looping when the first Mapping is
+   found which is not a ZoomMap or a UnitMap. */
+            } else if ( strcmp( class, "UnitMap" ) ) {
+               break;
+            }
+            imap1--;
+         }
+      }
+
+/* Similarly search adjacent higher-numbered ZoomMaps and UnitMaps and
+   accumulate their effective zoom factors. */
+      imap2 = where;
+      while ( astOK && ( ( imap2 + 1 ) < *nmap ) ) {
+         map = ( *map_list )[ imap2 + 1 ];
+         class = astGetClass( map );
+         if ( astOK ) {
+            if ( !strcmp( class, "ZoomMap" ) ) {
+               if ( ( *invert_list )[ imap2 + 1 ] ) {
+                  zoom /= astGetZoom( map );
+               } else {
+                  zoom *= astGetZoom( map );
+               }
+            } else if ( strcmp( class, "UnitMap" ) ) {
+               break;
+            }
+            imap2++;
+         }
+      }
+
+/* Determine how many Mappings can be eliminated by condensing those
+   found above into a single Mapping. */
+      ngone = imap2 - imap1;
+
+/* Determine if the replacement Mapping can be a UnitMap. This will be
+   the case only if the accumulated zoom factor is unity (within some
+   tolerable error). */
+      unit = ( fabs( zoom - 1.0 ) <= ( 8.0 * DBL_EPSILON ) );
+
+/* Determine if simplification is possible. This will be so if (a)
+   Mappings can be eliminated ("ngone" is non-zero), or (b) the
+   replacement can be a UnitMap, or (c) where there was initially only
+   one ZoomMap, its invert flag was set (it will always be cleared in
+   the replacement Mapping). */
+      simpler = ngone || unit || ( *invert_list )[ where ];
+
+/* Do nothing more unless simplification is possible. */
+      if ( simpler ) {
+
+/* Obtain the number of input/output coordinates for the replacement
+   Mapping and create the appropriate replacement. */
+         nin = astGetNin( ( *map_list )[ where ] );
+         if ( unit ) {
+            new = (AstMapping *) astUnitMap( nin, "", status );
+         } else {
+            new = (AstMapping *) astZoomMap( nin, zoom, "", status );
+         }
+      }
+
+/* In parallel. */
+/* ------------ */
+/* Handle the case where the Mappings are connected in parallel. */
+   } else {
+
+/* Obtain the number of input/output coordinates for the nominated Mapping. */
+      nin = astGetNin( ( *map_list )[ where ] );
+
+/* Search adjacent lower-numbered Mappings and identify the class to
+   which they belong. */
+      imap1 = where;
+      while ( astOK && ( ( imap1 - 1 ) >= 0 ) ) {
+         map = ( *map_list )[ imap1 - 1 ];
+         class = astGetClass( map );
+         if ( astOK ) {
+
+/* Quit looping when the first Mapping is found which is not a ZoomMap
+   or a UnitMap. */
+            if ( strcmp( class, "ZoomMap" ) &&
+                 strcmp( class, "UnitMap" ) ) break;
+
+/* Accumulate the total number of input/output coordinates for each
+   adjacent ZoomMap and UnitMap found. */
+            nin += astGetNin( map );
+            imap1--;
+         }
+      }
+
+/* Similarly search adjacent higher-numbered Mappings and accumulate
+   the number of input/output coordinates.*/
+      imap2 = where;
+      while ( astOK && ( ( imap2 + 1 ) < *nmap ) ) {
+         map = ( *map_list )[ imap2 + 1 ];
+         class = astGetClass( map );
+         if ( astOK ) {
+            if ( strcmp( class, "ZoomMap" ) &&
+                 strcmp( class, "UnitMap" ) ) break;
+            nin += astGetNin( map );
+            imap2++;
+         }
+      }
+
+/* Allocate memory for an array of zoom factors, one for each
+   input/output coordinate in the replacement Mapping. */
+      zooms = astMalloc( sizeof( double ) * (size_t) nin );
+      if ( astOK ) {
+
+/* Initialise. */
+         nzoom = 0;
+         minzoom = DBL_MAX;
+         maxzoom = -DBL_MAX;
+
+/* Loop through all the ZoomMaps and UnitMaps being merged and again
+   identify the class to which they belong. */
+         for ( imap = imap1; astOK && ( imap <= imap2 ); imap++ ) {
+            map = ( *map_list )[ imap ];
+            class = astGetClass( map );
+            if ( astOK ) {
+
+/* Set a default zoom factor of unity (for UnitMaps). If the Mapping
+   is a ZoomMap, replace this with the effective zoom factor, taking
+   account of the associated invert flag. */
+               zoom = 1.0;
+               if ( !strcmp( class, "ZoomMap" ) ) {
+                  if ( ( *invert_list )[ imap ] ) {
+                     zoom = 1.0 / astGetZoom( map );
+                  } else {
+                     zoom = astGetZoom( map );
+                  }
+               }
+
+/* Replicate the zoom factor in the zoom factor array, once for each
+   input/output coordinate associated with the current Mapping. */
+               ncoord = astGetNin( map );
+               for ( coord = 0; coord < ncoord; coord++ ) {
+                  zooms[ nzoom++ ] = zoom;
+               }
+
+/* Store the minimum and maximum zoom factors encountered. */
+               if ( zoom < minzoom ) minzoom = zoom;
+               if ( zoom > maxzoom ) maxzoom = zoom;
+            }
+         }
+
+/* Determine how many Mappings can be eliminated by condensing those
+   found above into a single Mapping. */
+         ngone = imap2 - imap1;
+
+/* Determine whether the replacement Mapping can be a single
+   ZoomMap. This will be so if all the effective zoom factors were the
+   same. */
+         single = ( minzoom == maxzoom );
+
+/* Determine if the replacement Mapping can be a UnitMap. This will be
+   so if all the effective zoom factors were equal to unity. */
+         unit = single && ( minzoom == 1.0 );
+
+/* Determine if simplification is possible. This will be so if (a)
+   Mappings can be eliminated ("ngone" is non-zero), or (b) the
+   replacement can be a UnitMap, or (c) where there was initially only
+   one ZoomMap, its invert flag was set (it will always be cleared in
+   the replacement Mapping). */
+         simpler = ngone || unit || ( *invert_list )[ where ];
+
+/* Do nothing more unless simplification is possible. */
+         if ( simpler ) {
+
+/* Create a replacement UnitMap or ZoomMap if appropriate. */
+            if ( unit ) {
+               new = (AstMapping *) astUnitMap( nin, "", status );
+            } else if ( single ) {
+               new = (AstMapping *) astZoomMap( nin, minzoom, "", status );
+
+/* Otherwise, replace the original ZoomMaps and UnitMaps with a
+   diagonal MatrixMap containing the zoom factors as its diagonal
+   elements. */
+            } else {
+               new = (AstMapping *) astMatrixMap( nin, nin, 1, zooms, "", status );
+            }
+         }
+      }
+
+/* Free the array of zoom factors. */
+      zooms = astFree( zooms );
+   }
+
+/* If OK, and simplification is possible, we now have a replacement
+   Mapping and can insert it into the Mapping list. */
+   if ( astOK ) {
+      if ( simpler ) {
+
+/* Annul the pointers to all the ZoomMaps that are being replaced. */
+         for ( imap = imap1; imap <= imap2; imap++ ) {
+            ( *map_list )[ imap ] = astAnnul( ( *map_list )[ imap ] );
+         }
+
+/* Insert the new pointer and the associated invert flag. */
+         ( *map_list )[ imap1 ] = new;
+         ( *invert_list )[ imap1 ] = 0;
+
+/* Loop to close the resulting gap by moving subsequent elements down
+   in the arrays. */
+         for ( imap = imap2 + 1; imap < *nmap; imap++ ) {
+            ( *map_list )[ imap - ngone ] = ( *map_list )[ imap ];
+            ( *invert_list )[ imap - ngone ] = ( *invert_list )[ imap ];
+         }
+
+/* Clear the vacated elements at the end. */
+         for ( imap = *nmap - ngone; imap < *nmap; imap++ ) {
+            ( *map_list )[ imap ] = NULL;
+            ( *invert_list )[ imap ] = 0;
+         }
+
+/* Decrement the Mapping count and return the index of the first
+   modified element. */
+         ( *nmap ) -= ngone;
+         result = imap1;
+      }
+
+/* If an error occurred, but a new Mapping has been created, then
+   annul it. */
+   } else {
+      if ( new ) new = astAnnul( new );
+   }
+
+/* If an error occurred, clear the returned result. */
+   if ( !astOK ) result = -1;
+
+/* Return the result. */
+   return result;
+}
+
+static int *MapSplit( AstMapping *this_map, int nin, const int *in, AstMapping **map, int *status ){
+/*
+*  Name:
+*     MapSplit
+
+*  Purpose:
+*     Create a Mapping representing a subset of the inputs of an existing
+*     ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     int *MapSplit( AstMapping *this, int nin, const int *in, AstMapping **map, int *status )
+
+*  Class Membership:
+*     ZoomMap method (over-rides the protected astMapSplit method
+*     inherited from the Mapping class).
+
+*  Description:
+*     This function creates a new Mapping by picking specified inputs from
+*     an existing ZoomMap. This is only possible if the specified inputs
+*     correspond to some subset of the ZoomMap outputs. That is, there
+*     must exist a subset of the ZoomMap outputs for which each output
+*     depends only on the selected ZoomMap inputs, and not on any of the
+*     inputs which have not been selected. If this condition is not met
+*     by the supplied ZoomMap, then a NULL Mapping is returned.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap to be split (the ZoomMap is not actually
+*        modified by this function).
+*     nin
+*        The number of inputs to pick from "this".
+*     in
+*        Pointer to an array of indices (zero based) for the inputs which
+*        are to be picked. This array should have "nin" elements. If "Nin"
+*        is the number of inputs of the supplied ZoomMap, then each element
+*        should have a value in the range zero to Nin-1.
+*     map
+*        Address of a location at which to return a pointer to the new
+*        Mapping. This Mapping will have "nin" inputs (the number of
+*        outputs may be different to "nin"). A NULL pointer will be
+*        returned if the supplied ZoomMap has no subset of outputs which
+*        depend only on the selected inputs.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     A pointer to a dynamically allocated array of ints. The number of
+*     elements in this array will equal the number of outputs for the
+*     returned Mapping. Each element will hold the index of the
+*     corresponding output in the supplied ZoomMap. The array should be
+*     freed using astFree when no longer needed. A NULL pointer will
+*     be returned if no output Mapping can be created.
+
+*  Notes:
+*     - If this function is invoked with the global error status set,
+*     or if it should fail for any reason, then NULL values will be
+*     returned as the function value and for the "map" pointer.
+*/
+
+/* Local Variables: */
+   AstZoomMap *this;          /* Pointer to ZoomMap structure */
+   int *result;               /* Pointer to returned array */
+   int i;                     /* Loop count */
+   int iin;                   /* Mapping input index */
+   int mnin;                  /* No. of Mapping inputs */
+   int ok;                    /* Are input indices OK? */
+
+/* Initialise */
+   result = NULL;
+   *map = NULL;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Get a pointer to the ZoomMap structure. */
+   this = (AstZoomMap *) this_map;
+
+/* Allocate memory for the returned array and create a ZoomMap with the
+   required number of axes. */
+   result = astMalloc( sizeof( int )*(size_t) nin );
+   *map = (AstMapping *) astZoomMap( nin, astGetZoom( this ), "", status );
+
+/* Set its Invert attribute to be like the supplied ZoomMap. */
+   astSetInvert( *map, astGetInvert( this ) );
+
+/* Check pointers can be used safely. */
+   if( astOK ) {
+
+/* Store the required output axis indices. At the same time check that each
+   axis is valid. */
+      mnin = astGetNin( this );
+      ok = 1;
+      for( i = 0; i < nin; i++ ) {
+         iin = in[ i ];
+         if( iin >= 0 && iin < mnin ) {
+            result[ i ] = iin;
+         } else {
+            ok = 0;
+            break;
+         }
+      }
+
+/* If the "in" array contained any invalid values, free the returned
+   resources. */
+      if( !ok ) {
+         result = astFree( result );
+         *map = astAnnul( *map );
+      }
+   }
+
+/* Free returned resources if an error has occurred. */
+   if( !astOK ) {
+      result = astFree( result );
+      *map = astAnnul( *map );
+   }
+
+/* Return the list of output indices. */
+   return result;
+}
+
+static double Rate( AstMapping *this, double *at, int ax1, int ax2, int *status ){
+/*
+*  Name:
+*     Rate
+
+*  Purpose:
+*     Calculate the rate of change of a Mapping output.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     result = Rate( AstMapping *this, double *at, int ax1, int ax2, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (overrides the astRate method inherited
+*     from the Mapping class ).
+
+*  Description:
+*     This function returns the rate of change of a specified output of
+*     the supplied Mapping with respect to a specified input, at a
+*     specified input position.
+
+*  Parameters:
+*     this
+*        Pointer to the Mapping to be applied.
+*     at
+*        The address of an array holding the axis values at the position
+*        at which the rate of change is to be evaluated. The number of
+*        elements in this array should equal the number of inputs to the
+*        Mapping.
+*     ax1
+*        The index of the Mapping output for which the rate of change is to
+*        be found (output numbering starts at 0 for the first output).
+*     ax2
+*        The index of the Mapping input which is to be varied in order to
+*        find the rate of change (input numbering starts at 0 for the first
+*        input).
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     The rate of change of Mapping output "ax1" with respect to input
+*     "ax2", evaluated at "at", or AST__BAD if the value cannot be
+*     calculated.
+
+*/
+
+/* Local Variables: */
+   double result;
+
+/* Check inherited status */
+   if( !astOK ) return AST__BAD;
+
+/* Result is zero if the axes differ */
+   if( ax1 != ax2 ) {
+      result = 0.0;
+
+/* Otherwise, get the zoom factor. */
+   } else {
+      result = astGetZoom( (AstZoomMap *) this );
+
+/* If the ZoomMap has been inverted, return the reciprocal of the zoom
+   factor. */
+      if ( astGetInvert( this ) ) {
+         if( result != AST__BAD && result != 0.0 ) {
+            result = 1.0/result;
+         } else {
+            result = AST__BAD;
+         }
+      }
+   }
+
+/* Return the result. */
+   return result;
+}
+
+static void SetAttrib( AstObject *this_object, const char *setting, int *status ) {
+/*
+*  Name:
+*     SetAttrib
+
+*  Purpose:
+*     Set an attribute value for a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     void SetAttrib( AstObject *this, const char *setting )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the astSetAttrib protected
+*     method inherited from the Mapping class).
+
+*  Description:
+*     This function assigns an attribute value for a ZoomMap, the
+*     attribute and its value being specified by means of a string of
+*     the form:
+*
+*        "attribute= value "
+*
+*     Here, "attribute" specifies the attribute name and should be in
+*     lower case with no white space present. The value to the right
+*     of the "=" should be a suitable textual representation of the
+*     value to be assigned and this will be interpreted according to
+*     the attribute's data type.  White space surrounding the value is
+*     only significant for string attributes.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap.
+*     setting
+*        Pointer to a null-terminated string specifying the new attribute
+*        value.
+*/
+
+/* Local Variables: */
+   AstZoomMap *this;             /* Pointer to the ZoomMap structure */
+   double zoom;                  /* Zoom attribute value */
+   int len;                      /* Length of setting string */
+   int nc;                       /* Number of characters read by astSscanf */
+
+/* Check the global error status. */
+   if ( !astOK ) return;
+
+/* Obtain a pointer to the ZoomMap structure. */
+   this = (AstZoomMap *) this_object;
+
+/* Obtain the length of the setting string. */
+   len = (int) strlen( setting );
+
+/* Test for each recognised attribute in turn, using "astSscanf" to parse
+   the setting string and extract the attribute value (or an offset to
+   it in the case of string values). In each case, use the value set
+   in "nc" to check that the entire string was matched. Once a value
+   has been obtained, use the appropriate method to set it. */
+
+/* Zoom. */
+/* ----- */
+   if ( nc = 0,
+        ( 1 == astSscanf( setting, "zoom= %lf %n", &zoom, &nc ) )
+        && ( nc >= len ) ) {
+      astSetZoom( this, zoom );
+
+/* If the attribute is still not recognised, pass it on to the parent
+   method for further interpretation. */
+   } else {
+      (*parent_setattrib)( this_object, setting, status );
+   }
+}
+
+static int TestAttrib( AstObject *this_object, const char *attrib, int *status ) {
+/*
+*  Name:
+*     TestAttrib
+
+*  Purpose:
+*     Test if a specified attribute value is set for a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     int TestAttrib( AstObject *this, const char *attrib, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the astTestAttrib protected
+*     method inherited from the Mapping class).
+
+*  Description:
+*     This function returns a boolean result (0 or 1) to indicate whether
+*     a value has been set for one of a ZoomMap's attributes.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap.
+*     attrib
+*        Pointer to a null-terminated string specifying the attribute
+*        name.  This should be in lower case with no surrounding white
+*        space.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     One if a value has been set, otherwise zero.
+
+*  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: */
+   AstZoomMap *this;             /* Pointer to the ZoomMap structure */
+   int result;                   /* Result value to return */
+
+/* Initialise. */
+   result = 0;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Obtain a pointer to the ZoomMap structure. */
+   this = (AstZoomMap *) this_object;
+
+/* Check the attribute name and test the appropriate attribute. */
+
+/* Zoom. */
+/* ----- */
+   if ( !strcmp( attrib, "zoom" ) ) {
+      result = astTestZoom( this );
+
+/* If the attribute is still not recognised, pass it on to the parent
+   method for further interpretation. */
+   } else {
+      result = (*parent_testattrib)( this_object, attrib, status );
+   }
+
+/* Return the result, */
+   return result;
+}
+
+static AstPointSet *Transform( AstMapping *this, AstPointSet *in,
+                               int forward, AstPointSet *out, int *status ) {
+/*
+*  Name:
+*     Transform
+
+*  Purpose:
+*     Apply a ZoomMap to transform a set of points.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     AstPointSet *Transform( AstMapping *this, AstPointSet *in,
+*                             int forward, AstPointSet *out, int *status )
+
+*  Class Membership:
+*     ZoomMap member function (over-rides the astTransform protected
+*     method inherited from the Mapping class).
+
+*  Description:
+*     This function takes a ZoomMap and a set of points encapsulated in a
+*     PointSet and transforms the points so as to apply the required zoom
+*     factor.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap.
+*     in
+*        Pointer to the PointSet holding the input coordinate data.
+*     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 ZoomMap 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: */
+   AstPointSet *result;          /* Pointer to output PointSet */
+   AstZoomMap *map;              /* Pointer to ZoomMap to be applied */
+   double **ptr_in;              /* Pointer to input coordinate data */
+   double **ptr_out;             /* Pointer to output coordinate data */
+   double scale;                 /* Scale factor to implement zoom */
+   int coord;                    /* Loop counter for coordinates */
+   int ncoord_in;                /* Number of coordinates per input point */
+   int npoint;                   /* Number of points */
+   int point;                    /* Loop counter for points */
+
+/* Check the global error status. */
+   if ( !astOK ) return NULL;
+
+/* Obtain a pointer to the ZoomMap. */
+   map = (AstZoomMap *) this;
+
+/* Apply the parent mapping using the stored pointer to the Transform member
+   function inherited from the parent Mapping class. This function validates
+   all arguments and generates an output PointSet if necessary, but does not
+   actually transform any coordinate values. */
+   result = (*parent_transform)( this, in, forward, out, status );
+
+/* We will now extend the parent astTransform method by performing the
+   calculations needed to generate the output coordinate values. */
+
+/* Determine the numbers of points and coordinates per point from the input
+   PointSet and obtain pointers for accessing the input and output coordinate
+   values. */
+   ncoord_in = astGetNcoord( in );
+   npoint = astGetNpoint( in );
+   ptr_in = astGetPoints( in );
+   ptr_out = astGetPoints( result );
+
+/* Determine whether to apply the forward or inverse mapping, according to the
+   direction specified and whether the mapping has been inverted. */
+   if ( astGetInvert( map ) ) forward = !forward;
+
+/* Perform coordinate arithmetic. */
+/* ------------------------------ */
+/* Generate the coordinate scale factor, according to the direction
+   of mapping required. */
+   scale = astGetZoom( map );
+   if ( !forward && astOK ) scale = 1.0 / scale;
+
+/* Loop to apply the scale factor to all the coordinate values, checking for
+   (and propagating) bad values in the process. */
+   if ( astOK ) {
+      for ( coord = 0; coord < ncoord_in; coord++ ) {
+         for ( point = 0; point < npoint; point++ ) {
+            if ( ptr_in[ coord ][ point ] == AST__BAD ) {
+               ptr_out[ coord ][ point ] = AST__BAD;
+            } else {
+               ptr_out[ coord ][ point ] = ptr_in[ coord ][ point ] * scale;
+            }
+         }
+      }
+   }
+
+/* Return a pointer to the output PointSet. */
+   return result;
+}
+
+/* Functions which access class attributes. */
+/* ---------------------------------------- */
+/* Implement member functions to access the attributes associated with
+   this class using the macros defined for this purpose in the
+   "object.h" file. For a description of each attribute, see the class
+   interface (in the associated .h file). */
+
+/*
+*att++
+*  Name:
+*     Zoom
+
+*  Purpose:
+*     ZoomMap scale factor.
+
+*  Type:
+*     Public attribute.
+
+*  Synopsis:
+*     Double precision.
+
+*  Description:
+*     This attribute holds the ZoomMap scale factor, by which
+*     coordinate values are multiplied (by the forward transformation)
+*     or divided (by the inverse transformation). The default value
+*     is unity.
+*
+c     Note that if a ZoomMap is inverted (e.g. by using astInvert),
+f     Note that if a ZoomMap is inverted (e.g. by using AST_INVERT),
+*     then the reciprocal of this zoom factor will, in effect, be
+*     used.
+*
+*     In general, Mapping attributes cannot be changed after the Mapping
+*     has been created (the exception to this is the Invert attribute,
+*     which can be changed at any time). However, several of the oldest
+*     Mapping classes - including the ZoomMap class - were introduced
+*     into the AST library before this restriction was enforced. To
+*     reduce the chances of breaking existing software, the attributes of
+*     such Mappings may still be changed, but only for Mapping instances
+*     that have exactly one active reference. In other words, an error will
+*     be reported if an attempt is made to set or clear an attribute of a
+*     Mapping (other than the Invert attribute) if that Mapping has been
+*     cloned. Mappings are cloned when they are incorporated into another
+*     object such as a CmpMap or FrameSet, or when the
+c     astClone
+f     AST_CLONE
+*     function is used.
+
+*  Applicability:
+*     ZoomMap
+*        All ZoomMaps have this attribute.
+
+*  Notes:
+*     - The Zoom attribute may not be set to zero.
+*att--
+*/
+/* This ia a double value with a value of 0.0 when undefined but
+   yielding a default of 1.0. Setting it explicitly to 0.0 is not
+   permitted except via astClearZoom. */
+astMAKE_CLEAR1(ZoomMap,Zoom,zoom,0.0)
+astMAKE_GET(ZoomMap,Zoom,double,1.0,( ( this->zoom == 0.0 ) ?
+                                      1.0 : this->zoom ))
+
+/* Check for an attempt to set a value of zero and report an error if
+   necessary (leaving the Zoom value unchanged). */
+astMAKE_SET1(ZoomMap,Zoom,double,zoom,(
+            ( value != 0.0 ) ?
+            value :
+            ( astError( AST__ZOOMI,
+                       "astSetZoom(%s): A zoom factor of zero is not allowed.", status,
+                        astGetClass( this ) ),
+              this->zoom ) ))
+astMAKE_TEST(ZoomMap,Zoom,( this->zoom != 0.0 ))
+
+/* Copy constructor. */
+/* ----------------- */
+/* No copy constructor is needed, as a byte-by-byte copy suffices. */
+
+/* Destructor. */
+/* ----------- */
+/* No destructor is needed as no memory, etc. needs freeing. */
+
+/* Dump function. */
+/* -------------- */
+static void Dump( AstObject *this_object, AstChannel *channel, int *status ) {
+/*
+*  Name:
+*     Dump
+
+*  Purpose:
+*     Dump function for ZoomMap 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 ZoomMap class to an output Channel.
+
+*  Parameters:
+*     this
+*        Pointer to the ZoomMap 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: */
+   AstZoomMap *this;             /* Pointer to the ZoomMap structure */
+   double dval;                  /* Double value */
+   int set;                      /* Attribute value set? */
+
+/* Check the global error status. */
+   if ( !astOK ) return;
+
+/* Obtain a pointer to the ZoomMap structure. */
+   this = (AstZoomMap *) this_object;
+
+/* Write out values representing the instance variables for the
+   ZoomMap 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. */
+
+/* Zoom. */
+/* ----- */
+   set = TestZoom( this, status );
+   dval = set ? GetZoom( this, status ) : astGetZoom( this );
+   astWriteDouble( channel, "Zoom", set, 1, dval, "Zoom factor" );
+}
+
+/* Standard class functions. */
+/* ========================= */
+/* Implement the astIsAZoomMap and astCheckZoomMap functions using the macros
+   defined for this purpose in the "object.h" header file. */
+astMAKE_ISA(ZoomMap,Mapping)
+astMAKE_CHECK(ZoomMap)
+
+AstZoomMap *astZoomMap_( int ncoord, double zoom, const char *options, int *status, ...) {
+/*
+*++
+*  Name:
+c     astZoomMap
+f     AST_ZOOMMAP
+
+*  Purpose:
+*     Create a ZoomMap.
+
+*  Type:
+*     Public function.
+
+*  Synopsis:
+c     #include "zoommap.h"
+c     AstZoomMap *astZoomMap( int ncoord, double zoom,
+c                             const char *options, ... )
+f     RESULT = AST_ZOOMMAP( NCOORD, ZOOM, OPTIONS, STATUS )
+
+*  Class Membership:
+*     ZoomMap constructor.
+
+*  Description:
+*     This function creates a new ZoomMap and optionally initialises its
+*     attributes.
+*
+*     A ZoomMap is a Mapping which "zooms" a set of points about the
+*     origin by multiplying all coordinate values by the same scale
+*     factor (the inverse transformation is performed by dividing by
+*     this scale factor).
+
+*  Parameters:
+c     ncoord
+f     NCOORD = INTEGER (Given)
+*        The number of coordinate values for each point to be
+*        transformed (i.e. the number of dimensions of the space in
+*        which the points will reside). The same number is applicable
+*        to both input and output points.
+c     zoom
+f     ZOOM = DOUBLE PRECISION (Given)
+*        Initial scale factor by which coordinate values should be
+*        multiplied (by the forward transformation) or divided (by the
+*        inverse transformation). This factor may subsequently be
+*        changed via the ZoomMap's Zoom attribute. It may be positive
+*        or negative, but should not be zero.
+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 ZoomMap. 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 ZoomMap. 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     astZoomMap()
+f     AST_ZOOMMAP = INTEGER
+*        A pointer to the new ZoomMap.
+
+*  Notes:
+*     - 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.
+
+*  Status Handling:
+*     The protected interface to this function includes an extra
+*     parameter at the end of the parameter list descirbed above. This
+*     parameter is a pointer to the integer inherited status
+*     variable: "int *status".
+
+*--
+*/
+
+/* Local Variables: */
+   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
+   AstZoomMap *new;              /* Pointer to new ZoomMap */
+   va_list args;                 /* Variable argument list */
+
+/* Get a pointer to the thread specific global data structure. */
+   astGET_GLOBALS(NULL);
+
+/* Check the global status. */
+   if ( !astOK ) return NULL;
+
+/* Initialise the ZoomMap, allocating memory and initialising the
+   virtual function table as well if necessary. */
+   new = astInitZoomMap( NULL, sizeof( AstZoomMap ), !class_init, &class_vtab,
+                         "ZoomMap", ncoord, zoom );
+
+/* 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 ZoomMap'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 ZoomMap. */
+   return new;
+}
+
+AstZoomMap *astZoomMapId_( int ncoord, double zoom,
+                           const char *options, ... ) {
+/*
+*  Name:
+*     astZoomMapId_
+
+*  Purpose:
+*     Create a ZoomMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     AstZoomMap *astZoomMapId_( int ncoord, double zoom,
+*                                const char *options, ... )
+
+*  Class Membership:
+*     ZoomMap constructor.
+
+*  Description:
+*     This function implements the external (public) interface to the
+*     astZoomMap constructor function. It returns an ID value (instead
+*     of a true C pointer) to external users, and must be provided
+*     because astZoomMap_ has a variable argument list which cannot be
+*     encapsulated in a macro (where this conversion would otherwise
+*     occur).
+*
+*     The variable argument list also prevents this function from
+*     invoking astZoomMap_ directly, so it must be a re-implementation
+*     of it in all respects, except for the final conversion of the
+*     result to an ID value.
+
+*  Parameters:
+*     As for astZoomMap_.
+
+*  Returned Value:
+*     The ID value associated with the new ZoomMap.
+*/
+
+/* Local Variables: */
+   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
+   AstZoomMap *new;              /* Pointer to new ZoomMap */
+   va_list args;                 /* Variable argument list */
+
+   int *status;                  /* Pointer to inherited status value */
+
+/* Get a pointer to the inherited status value. */
+   status = astGetStatusPtr;
+
+/* Get a pointer to the thread specific global data structure. */
+   astGET_GLOBALS(NULL);
+
+/* Check the global status. */
+   if ( !astOK ) return NULL;
+
+/* Initialise the ZoomMap, allocating memory and initialising the
+   virtual function table as well if necessary. */
+   new = astInitZoomMap( NULL, sizeof( AstZoomMap ), !class_init, &class_vtab,
+                         "ZoomMap", ncoord, zoom );
+
+/* 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 ZoomMap'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 ZoomMap. */
+   return astMakeId( new );
+}
+
+AstZoomMap *astInitZoomMap_( void *mem, size_t size, int init,
+                             AstZoomMapVtab *vtab, const char *name,
+                             int ncoord, double zoom, int *status ) {
+/*
+*+
+*  Name:
+*     astInitZoomMap
+
+*  Purpose:
+*     Initialise a ZoomMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     AstZoomMap *astInitZoomMap( void *mem, size_t size, int init,
+*                                 AstZoomMapVtab *vtab, const char *name,
+*                                 int ncoord, double zoom )
+
+*  Class Membership:
+*     ZoomMap initialiser.
+
+*  Description:
+*     This function is provided for use by class implementations to initialise
+*     a new ZoomMap object. It allocates memory (if necessary) to accommodate
+*     the ZoomMap plus any additional data associated with the derived class.
+*     It then initialises a ZoomMap 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 ZoomMap at the start of the memory passed via the
+*     "vtab" parameter.
+
+*  Parameters:
+*     mem
+*        A pointer to the memory in which the ZoomMap is to be initialised.
+*        This must be of sufficient size to accommodate the ZoomMap data
+*        (sizeof(ZoomMap)) 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 ZoomMap (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 ZoomMap
+*        structure, so a valid value must be supplied even if not required for
+*        allocating memory.
+*     init
+*        A logical flag indicating if the ZoomMap'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 ZoomMap.
+*     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).
+*     ncoord
+*        The number of coordinate values per point.
+*     zoom
+*        The scale factor by which coordinate values are multiplied (by the
+*        forward mapping) or divided (by the inverse mapping). This factor may
+*        not be zero.
+
+*  Returned Value:
+*     A pointer to the new ZoomMap.
+
+*  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: */
+   AstZoomMap *new;              /* Pointer to new ZoomMap */
+
+/* Check the global status. */
+   if ( !astOK ) return NULL;
+
+/* If necessary, initialise the virtual function table. */
+   if ( init ) astInitZoomMapVtab( vtab, name );
+
+/* Initialise. */
+   new = NULL;
+
+/* Check the initialisation value(s) for validity, reporting an error if
+   necessary. Prefix the error report with the name of the function and the
+   class of object being processed. */
+   if ( zoom == 0.0 ) {
+      astError( AST__ZOOMI, "astInitZoomMap(%s): A zoom factor of zero is not "
+                "allowed.", status, name );
+   } else {
+
+/* Initialise a Mapping structure (the parent class) as the first component
+   within the ZoomMap structure, allocating memory if necessary. Specify that
+   the Mapping should be defined in both the forward and inverse directions. */
+      new = (AstZoomMap *) astInitMapping( mem, size, 0,
+                                           (AstMappingVtab *) vtab, name,
+                                           ncoord, ncoord, 1, 1 );
+
+      if ( astOK ) {
+
+/* Initialise the ZoomMap data. */
+/* ---------------------------- */
+/* Store the zoom factor. */
+         new->zoom = zoom;
+
+/* If an error occurred, clean up by deleting the new ZoomMap. */
+         if ( !astOK ) new = astDelete( new );
+      }
+   }
+
+/* Return a pointer to the new ZoomMap. */
+   return new;
+}
+
+AstZoomMap *astLoadZoomMap_( void *mem, size_t size,
+                             AstZoomMapVtab *vtab, const char *name,
+                             AstChannel *channel, int *status ) {
+/*
+*+
+*  Name:
+*     astLoadZoomMap
+
+*  Purpose:
+*     Load a ZoomMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "zoommap.h"
+*     AstZoomMap *astLoadZoomMap( void *mem, size_t size,
+*                                 AstZoomMapVtab *vtab, const char *name,
+*                                 AstChannel *channel )
+
+*  Class Membership:
+*     ZoomMap loader.
+
+*  Description:
+*     This function is provided to load a new ZoomMap 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
+*     ZoomMap 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 ZoomMap at the start of the memory
+*     passed via the "vtab" parameter.
+
+
+*  Parameters:
+*     mem
+*        A pointer to the memory into which the ZoomMap is to be
+*        loaded.  This must be of sufficient size to accommodate the
+*        ZoomMap data (sizeof(ZoomMap)) 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 ZoomMap (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 ZoomMap 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(AstZoomMap) is used instead.
+*     vtab
+*        Pointer to the start of the virtual function table to be
+*        associated with the new ZoomMap. If this is NULL, a pointer
+*        to the (static) virtual function table for the ZoomMap 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 "ZoomMap" is used instead.
+
+*  Returned Value:
+*     A pointer to the new ZoomMap.
+
+*  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 */
+   AstZoomMap *new;              /* Pointer to the new ZoomMap */
+
+/* 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 ZoomMap. In this case the
+   ZoomMap belongs to this class, so supply appropriate values to be
+   passed to the parent class loader (and its parent, etc.). */
+   if ( !vtab ) {
+      size = sizeof( AstZoomMap );
+      vtab = &class_vtab;
+      name = "ZoomMap";
+
+/* If required, initialise the virtual function table for this class. */
+      if ( !class_init ) {
+         astInitZoomMapVtab( 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 ZoomMap. */
+   new = astLoadMapping( mem, size, (AstMappingVtab *) 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, "ZoomMap" );
+
+/* 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. */
+
+/* Zoom. */
+/* ----- */
+      new->zoom = astReadDouble( channel, "zoom", 0.0 );
+      if ( TestZoom( new, status ) ) SetZoom( new, new->zoom, status );
+
+/* If an error occurred, clean up by deleting the new ZoomMap. */
+      if ( !astOK ) new = astDelete( new );
+   }
+
+/* Return the new ZoomMap 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. */
+
+
+
+
+