update ast 8.6.2

1 files changed, 1838 insertions, 0 deletions

diff --git a/ast/selectormap.c b/ast/selectormap.c
new file mode 100644
index 0000000..87a6f45
--- /dev/null
+++ b/ast/selectormap.c
@@ -0,0 +1,1838 @@
+/*
+*class++
+*  Name:
+*     SelectorMap
+
+*  Purpose:
+*     A Mapping that locates positions within one of a set of alternate
+*     Regions.
+
+*  Constructor Function:
+c     astSelectorMap
+f     AST_SELECTORMAP
+
+*  Description:
+*     A SelectorMap is a Mapping that identifies which Region contains
+*     a given input position.
+*
+*     A SelectorMap encapsulates a number of Regions that all have the same
+*     number of axes and represent the same coordinate Frame. The number of
+*     inputs (Nin attribute) of the SelectorMap equals the number of axes
+*     spanned by one of the encapsulated Region. All SelectorMaps have only
+*     a single output. SelectorMaps do not define an inverse transformation.
+*
+*     For each input position, the forward transformation of a SelectorMap
+*     searches through the encapsulated Regions (in the order supplied when
+*     the SelectorMap was created) until a Region is found which contains
+*     the input position. The index associated with this Region is
+*     returned as the SelectorMap output value (the index value is the
+*     position of the Region within the list of Regions supplied when the
+*     SelectorMap was created, starting at 1 for the first Region). If an
+*     input position is not contained within any Region, a value of zero is
+*     returned by the forward transformation.
+*
+*     If a compound Mapping contains a SelectorMap in series with its own
+*     inverse, the combination of the two adjacent SelectorMaps will be
+*     replaced by a UnitMap when the compound Mapping is simplified using
+c     astSimplify.
+f     AST_SIMPLIFY.
+*
+*     In practice, SelectorMaps are often used in conjunction with SwitchMaps.
+
+*  Inheritance:
+*     The SelectorMap class inherits from the Mapping class.
+
+*  Attributes:
+*     The SelectorMap class does not define any new attributes beyond those
+*     which are applicable to all Mappings.
+
+*  Functions:
+c     The SelectorMap class does not define any new functions beyond those
+f     The SelectorMap 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:
+*     DSB: David S. Berry (Starlink)
+
+*  History:
+*     15-MAR-2006 (DSB):
+*        Original version.
+*     18-MAY-2006 (DSB):
+*        - Change logic for detecting interior points in function Transform.
+*        - Added BADVAL to contructor argument list.
+*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 SelectorMap
+
+/* 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 "mapping.h"             /* Coordinate Mappings (parent class) */
+#include "unitmap.h"             /* Unit Mappings */
+#include "channel.h"             /* I/O channels */
+#include "selectormap.h"         /* Interface definition for this class */
+
+/* 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>
+
+/* 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 int (* parent_getobjsize)( AstObject *, int * );
+static AstPointSet *(* parent_transform)( AstMapping *, AstPointSet *, int, AstPointSet *, 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(SelectorMap)
+
+/* Define macros for accessing each item of thread specific global data. */
+#define class_init astGLOBAL(SelectorMap,Class_Init)
+#define class_vtab astGLOBAL(SelectorMap,Class_Vtab)
+
+
+#include <pthread.h>
+
+
+#else
+
+
+/* Define the class virtual function table and its initialisation flag
+   as static variables. */
+static AstSelectorMapVtab 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. */
+AstSelectorMap *astSelectorMapId_( int, void **, double, const char *, ... );
+
+/* Prototypes for Private Member Functions. */
+/* ======================================== */
+static AstPointSet *Transform( AstMapping *, AstPointSet *, int, AstPointSet *, int * );
+static int Equal( AstObject *, AstObject *, int * );
+static int GetObjSize( AstObject *, int * );
+static int MapMerge( AstMapping *, int, int, int *, AstMapping ***, int **, int * );
+static void Copy( const AstObject *, AstObject *, int * );
+static void Delete( AstObject *, int * );
+static void Dump( AstObject *, AstChannel *, int * );
+
+#if defined(THREAD_SAFE)
+static int ManageLock( AstObject *, int, int, AstObject **, int * );
+#endif
+
+/* Member functions. */
+/* ================= */
+static int Equal( AstObject *this_object, AstObject *that_object, int *status ) {
+/*
+*  Name:
+*     Equal
+
+*  Purpose:
+*     Test if two SelectorMaps are equivalent.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     int Equal( AstObject *this, AstObject *that, int *status )
+
+*  Class Membership:
+*     SelectorMap 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 SelectorMaps are equivalent.
+
+*  Parameters:
+*     this
+*        Pointer to the first Object (a SelectorMap).
+*     that
+*        Pointer to the second Object.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     One if the SelectorMaps 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: */
+   AstSelectorMap *that;
+   AstSelectorMap *this;
+   int i;
+   int nin;
+   int nreg;
+   int result;
+
+/* Initialise. */
+   result = 0;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Obtain pointers to the two SelectorMap structures. */
+   this = (AstSelectorMap *) this_object;
+   that = (AstSelectorMap *) that_object;
+
+/* Check the second object is a SelectorMap. We know the first is a
+   SelectorMap since we have arrived at this implementation of the virtual
+   function. */
+   if( astIsASelectorMap( that ) ) {
+
+/* Check they have the same number of inputs. */
+      nin = astGetNin( this );
+      if( astGetNin( that ) == nin ) {
+
+/* Check they contain the same number of Regions, and have the same badval. */
+         nreg = this->nreg;
+         if( that->nreg == nreg ||
+             astEQUAL( that->badval, this->badval) ) {
+
+/* Loop over the Regions, breaking as soon as two unequal Regions are
+   found. */
+            result = 1;
+            for( i = 0; i < nreg; i++ ) {
+               if( !astEqual( this->reg[ i ], that->reg[ i ] ) ) {
+                  result = 0;
+                  break;
+               }
+            }
+         }
+      }
+   }
+
+/* If an error occurred, clear the result value. */
+   if ( !astOK ) result = 0;
+
+/* Return the result, */
+   return result;
+}
+
+static int GetObjSize( AstObject *this_object, int *status ) {
+/*
+*  Name:
+*     GetObjSize
+
+*  Purpose:
+*     Return the in-memory size of an Object.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     int GetObjSize( AstObject *this, int *status )
+
+*  Class Membership:
+*     SelectorMap member function (over-rides the astGetObjSize protected
+*     method inherited from the parent class).
+
+*  Description:
+*     This function returns the in-memory size of the supplied SelectorMap,
+*     in bytes.
+
+*  Parameters:
+*     this
+*        Pointer to the SelectorMap.
+*     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: */
+   AstSelectorMap *this;
+   int i;
+   int result;
+
+/* Initialise. */
+   result = 0;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Obtain a pointers to the SelectorMap structure. */
+   this = (AstSelectorMap *) this_object;
+
+/* Invoke the GetObjSize method inherited from the parent class, and then
+   add on any components of the class structure defined by this class
+   which are stored in dynamically allocated memory. */
+   result = (*parent_getobjsize)( this_object, status );
+
+   for( i = 0; i < this->nreg; i++ ) {
+      result += astGetObjSize( this->reg[ i ] );
+   }
+
+/* If an error occurred, clear the result value. */
+   if ( !astOK ) result = 0;
+
+/* Return the result, */
+   return result;
+}
+
+void astInitSelectorMapVtab_(  AstSelectorMapVtab *vtab, const char *name, int *status ) {
+/*
+*+
+*  Name:
+*     astInitSelectorMapVtab
+
+*  Purpose:
+*     Initialise a virtual function table for a SelectorMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     void astInitSelectorMapVtab( AstSelectorMapVtab *vtab, const char *name )
+
+*  Class Membership:
+*     SelectorMap vtab initialiser.
+
+*  Description:
+*     This function initialises the component of a virtual function
+*     table which is used by the SelectorMap 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 astIsASelectorMap) 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. */
+
+/* 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;
+   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;
+
+/* Store replacement pointers for methods which will be over-ridden by
+   new member functions implemented here. */
+   object->Equal = Equal;
+   mapping->MapMerge = MapMerge;
+
+/* Declare the copy constructor, destructor and class dump function. */
+   astSetCopy( vtab, Copy );
+   astSetDelete( vtab, Delete );
+   astSetDump( vtab, Dump, "SelectorMap", "Region identification Mapping" );
+
+/* 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:
+*     SelectorMap 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: */
+   AstSelectorMap *this;       /* Pointer to SelectorMap structure */
+   int i;                      /* Loop count */
+   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 SelectorMap structure. */
+   this = (AstSelectorMap *) 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. */
+   for( i = 0; i < this->nreg; i++ ) {
+      if( !result ) result = astManageLock( this->reg[ i ], mode, extra, fail );
+   }
+
+   return result;
+
+}
+#endif
+
+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 SelectorMap.
+
+*  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:
+*     SelectorMap 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 SelectorMap 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 SelectorMap 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 SelectorMap which is to be merged with
+*        its neighbours. This should be a cloned copy of the SelectorMap
+*        pointer contained in the array element "(*map_list)[where]"
+*        (see below). This pointer will not be annulled, and the
+*        SelectorMap it identifies will not be modified by this function.
+*     where
+*        Index in the "*map_list" array (below) at which the pointer
+*        to the nominated SelectorMap 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 *new;
+   AstRegion **sreg;
+   AstSelectorMap *map;
+   AstSelectorMap *slneb;
+   int equal;
+   int i;
+   int ilo;
+   int nreg;
+   int result;
+   int simp;
+
+/* Initialise.*/
+   result = -1;
+
+/* Check the inherited status. */
+   if ( !astOK ) return result;
+
+/* Get a pointer to this SelectorMap, and note the number of Regions. */
+   map = (AstSelectorMap *) this;
+   nreg = map->nreg;
+
+/* Attempt to simplify the SelectorMap on its own. */
+/* ============================================= */
+
+/* Try to simplify each of the encapsulated Regions, noting if any
+   simplification takes place. */
+   simp = 0;
+   sreg = astMalloc( sizeof( AstRegion * )*nreg );
+   if( astOK ) {
+      for( i = 0; i < nreg; i++ ) {
+         sreg[ i ] = astSimplify( map->reg[ i ] );
+         simp = simp || ( sreg[ i ] != map->reg[ i ] );
+      }
+
+/* If any simplification took place, construct a new SelectorMap from these
+   simplified Mappings. */
+      if( simp ) {
+         (void) astAnnul( ( *map_list )[ where ] );
+         ( *map_list )[ where ] = (AstMapping *) astSelectorMap( nreg,
+                                                          (void **) sreg,
+                                                          map->badval, "", status );
+         result = where;
+      }
+
+/* Release resources. */
+      if( sreg ) {
+         for( i = 0; i < nreg; i++ ) sreg[ i ] = astAnnul( sreg[ i ] );
+         sreg = astFree( sreg );
+      }
+   }
+
+/* If possible, merge the SelectorMap with a neighbouring SelectorMap. */
+/* =============================================================== */
+/* Only do this if no change was made above, and we are combining the
+   Mappings in series. */
+   if( result == -1 && series ) {
+
+/* Is the higher neighbour a SelectorMap? If so get a pointer to it, and
+   note the index of the lower of the two adjacent SelectorMaps. */
+      if( where < ( *nmap - 1 ) &&
+          astIsASelectorMap( ( *map_list )[ where + 1 ] ) ){
+         slneb = (AstSelectorMap *) ( *map_list )[ where + 1 ];
+         ilo = where;
+
+/* If not, is the lower neighbour a SelectorMap? If so get a pointer to it, and
+   note the index of the lower of the two adjacent SelectorMaps. */
+      } else if( where > 0 &&
+                 astIsASelectorMap( ( *map_list )[ where - 1 ] ) ){
+         slneb = (AstSelectorMap *) ( *map_list )[ where - 1 ];
+         ilo =  where - 1;
+
+      } else {
+         slneb = NULL;
+      }
+
+/* If a neighbouring SelectorMap was found, we can replace the pair by a
+   UnitMap if the two SelectorMaps are equal but have opposite values for
+   their Invert flags. Temporarily invert the neighbour, then compare
+   the two SelectorMaps for equality, then re-invert the neighbour. */
+      if( slneb ) {
+         astInvert( slneb );
+         equal = astEqual( map, slneb );
+         astInvert( slneb );
+
+/* If the two SelectorMaps are equal but opposite, annul the first of the two
+   Mappings, and replace it with a UnitMap. Also set the invert flag. */
+         if( equal ) {
+            new = (AstMapping *) astUnitMap( astGetNin( ( *map_list )[ ilo ] ), "", status );
+            (void) astAnnul( ( *map_list )[ ilo ] );
+            ( *map_list )[ ilo ] = new;
+            ( *invert_list )[ ilo ] = 0;
+
+/* Annul the second of the two Mappings, and shuffle down the rest of the
+   list to fill the gap. */
+            (void) astAnnul( ( *map_list )[ ilo + 1 ] );
+            for ( i = ilo + 2; i < *nmap; i++ ) {
+               ( *map_list )[ i - 1 ] = ( *map_list )[ i ];
+               ( *invert_list )[ i - 1 ] = ( *invert_list )[ i ];
+            }
+
+/* Clear the vacated element at the end. */
+            ( *map_list )[ *nmap - 1 ] = NULL;
+            ( *invert_list )[ *nmap - 1 ] = 0;
+
+/* Decrement the Mapping count and return the index of the first
+   modified element. */
+            ( *nmap )--;
+            result = where;
+         }
+      }
+   }
+
+/* If an error occurred, clear the result value. */
+   if ( !astOK ) result = -1;
+
+/* Return the result. */
+   return result;
+}
+
+static AstPointSet *Transform( AstMapping *this, AstPointSet *in,
+                               int forward, AstPointSet *out, int *status ) {
+/*
+*  Name:
+*     Transform
+
+*  Purpose:
+*     Apply a SelectorMap to transform a set of points.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     AstPointSet *Transform( AstMapping *this, AstPointSet *in,
+*                             int forward, AstPointSet *out, int *status )
+
+*  Class Membership:
+*     SelectorMap member function (over-rides the astTransform method inherited
+*     from the Mapping class).
+
+*  Description:
+*     This function takes a SelectorMap and a set of points encapsulated in a
+*     PointSet and transforms the points so as to apply the required Mapping.
+*     This implies applying each of the SelectorMap's component Mappings in turn,
+*     either in series or in parallel.
+
+*  Parameters:
+*     this
+*        Pointer to the SelectorMap.
+*     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 SelectorMap 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 *ps1;
+   AstPointSet *ps2;
+   AstPointSet *result;
+   AstPointSet *tps;
+   AstRegion *reg;
+   AstSelectorMap *map;
+   double **ptr_out;
+   double **ptr1;
+   double **ptr2;
+   double **tptr;
+   double *p2;
+   double *pout;
+   double badval;
+   int bad;
+   int closed;
+   int icoord;
+   int ipoint;
+   int ireg;
+   int ncoord;
+   int npoint;
+
+/* Check the global error status. */
+   if ( !astOK ) return NULL;
+
+/* Obtain a pointer to the SelectorMap. */
+   map = (AstSelectorMap *) 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 now extend the parent astTransform method by applying the component
+   Mappings of the SelectorMap to generate the output coordinate values. */
+
+/* Check we are implementing the original forward transformation (the
+   inverse transformation is not defined). */
+   if( forward != astGetInvert( this ) ) {
+
+/* Get the number of input axes and the number of points. */
+      ncoord = astGetNcoord( in );
+      npoint = astGetNpoint( in );
+
+/* Create two temporary PointSets to hold copies of the input points. */
+      ps1 = astCopy( in );
+      ptr1 = astGetPoints( ps1 );
+      ps2 = astPointSet( npoint, ncoord, "", status );
+      ptr2 = astGetPoints( ps2 );
+
+/* Get a pointer to the output data */
+      ptr_out = astGetPoints( result );
+      if( astOK ) {
+
+/* Initialise the output array to hold -1 at any points that have
+   bad input axis values, and zero at all other points. */
+         pout = ptr_out[ 0 ];
+         for( ipoint = 0; ipoint < npoint; ipoint++ ) {
+            bad = 0;
+            for( icoord = 0; icoord < ncoord; icoord++ ) {
+               if( ptr1[ icoord ][ ipoint ] == AST__BAD ) {
+                  bad = 1;
+                  break;
+               }
+            }
+            *(pout++) = bad ? -1 : 0;
+         }
+
+/* Loop round all Regions. */
+         for( ireg = 1; ireg <= map->nreg; ireg++ ) {
+            reg = map->reg[ ireg - 1 ];
+
+/* Temporarily Negate the Region. */
+            astNegate( reg );
+            closed = astGetClosed( reg );
+            astSetClosed( reg, !closed );
+
+/* Transform the remaining input positions. Good input positions which
+   are within the Region will be bad in the output. */
+            ps2 = astTransform( reg, ps1, 1, ps2 );
+
+/* Loop round all positions. */
+            p2 = ptr2[ 0 ];
+            pout = ptr_out[ 0 ];
+            for( ipoint = 0; ipoint < npoint; ipoint++, p2++, pout++ ) {
+
+/* Any position that has not already been assigned to a Region and is bad
+   in the output PointSet must be contained within the current Region, so
+   assign the (one-based) index of the current Region to the output element. */
+               if( *pout == 0 && *p2 == AST__BAD ) *pout = ireg;
+            }
+
+/* Negate the Region to get it back to its original state. */
+            astSetClosed( reg, closed );
+            astNegate( reg );
+
+/* Swap the input and output PointSets. */
+            tps = ps1;
+            ps1 = ps2;
+            ps2 = tps;
+            tptr = ptr1;
+            ptr1 = ptr2;
+            ptr2 = tptr;
+         }
+
+/* Replace -1 values in the output (that indicate that the input position
+   had at least one bad axis value) with the "badval".*/
+         badval = map->badval;
+         pout = ptr_out[ 0 ];
+         for( ipoint = 0; ipoint < npoint; ipoint++, pout++ ) {
+            if( *pout == -1 ) *pout = badval;
+         }
+      }
+
+/* Free resources. */
+      ps1 = astAnnul( ps1 );
+      ps2 = astAnnul( ps2 );
+   }
+
+/* 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 SelectorMap objects.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     void Copy( const AstObject *objin, AstObject *objout, int *status )
+
+*  Description:
+*     This function implements the copy constructor for SelectorMap 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
+*     Regions within the SelectorMap.
+*/
+
+/* Local Variables: */
+   AstSelectorMap *in;                /* Pointer to input SelectorMap */
+   AstSelectorMap *out;               /* Pointer to output SelectorMap */
+   int i;                             /* Loop count */
+
+/* Check the global error status. */
+   if ( !astOK ) return;
+
+/* Obtain pointers to the input and output SelectorMaps. */
+   in = (AstSelectorMap *) objin;
+   out = (AstSelectorMap *) objout;
+
+/* For safety, start by clearing any references to the input Regions. */
+   out->reg = NULL;
+   out->nreg = 0;
+
+/* Make copies of the Regions, and store pointers to them in the output
+   SelectorMap structure. */
+   out->reg = astMalloc( sizeof( AstRegion * )*( in->nreg ) );
+   if( astOK ) {
+      for( i = 0; i < in->nreg; i++ ) {
+         out->reg[ i ] = astCopy( in->reg[ i ] );
+      }
+      out->nreg = in->nreg;
+   }
+
+}
+
+/* Destructor. */
+/* ----------- */
+static void Delete( AstObject *obj, int *status ) {
+/*
+*  Name:
+*     Delete
+
+*  Purpose:
+*     Destructor for SelectorMap objects.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     void Delete( AstObject *obj, int *status )
+
+*  Description:
+*     This function implements the destructor for SelectorMap 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: */
+   AstSelectorMap *this;              /* Pointer to SelectorMap */
+   int i;
+
+/* Obtain a pointer to the SelectorMap structure. */
+   this = (AstSelectorMap *) obj;
+
+/* Free dynamically allocated resources. */
+   for( i = 0; i < this->nreg; i++ ) {
+      this->reg[ i ] = astAnnul( this->reg[ i ] );
+   }
+   this->reg = astFree( this->reg );
+
+/* Clear the remaining SelectorMap variables. */
+   this->nreg = 0;
+}
+
+/* Dump function. */
+/* -------------- */
+static void Dump( AstObject *this_object, AstChannel *channel, int *status ) {
+/*
+*  Name:
+*     Dump
+
+*  Purpose:
+*     Dump function for SelectorMap 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 SelectorMap class to an output Channel.
+
+*  Parameters:
+*     this
+*        Pointer to the SelectorMap 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: */
+   AstSelectorMap *this;
+   int i;
+   char buf[ 20 ];
+
+/* Check the global error status. */
+   if ( !astOK ) return;
+
+/* Obtain a pointer to the SelectorMap structure. */
+   this = (AstSelectorMap *) this_object;
+
+/* Write out values representing the instance variables for the SelectorMap
+   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. */
+
+/* Loop to dump each Region. */
+/* ------------------------- */
+/* The coordinate Frame of the Regions is defined by the first Region.
+   The Frame information is omitted from the second and subsequent
+   Regions by setting the protected RegionFS attribute to zero. */
+   for( i = 0; i < this->nreg; i++ ) {
+      sprintf( buf, "Reg%d", i + 1 );
+      if( i > 0 ) astSetRegionFS( this->reg[ i ], 0 );
+      astWriteObject( channel, buf, 1, 1, this->reg[ i ],
+                      "Region of input space" );
+      if( i > 0 ) astClearRegionFS( this->reg[ i ] );
+   }
+
+/* BadVal. */
+/* ------- */
+   if( this->badval != AST__BAD ) {
+      astWriteDouble( channel, "BadVal", 1, 1, this->badval,
+                      "Output value for bad input positions" );
+   }
+
+}
+
+/* Standard class functions. */
+/* ========================= */
+/* Implement the astIsASelectorMap and astCheckSelectorMap functions using the
+   macros defined for this purpose in the "object.h" header file. */
+astMAKE_ISA(SelectorMap,Mapping)
+astMAKE_CHECK(SelectorMap)
+
+AstSelectorMap *astSelectorMap_( int nreg, void **regs_void, double badval,
+                                 const char *options, int *status, ...) {
+/*
+*+
+*  Name:
+*     astSelectorMap
+
+*  Purpose:
+*     Create a SelectorMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     AstSelectorMap *astSelectorMap( int nreg, AstRegion **regs,
+*                                     double badval, const char *options, ... )
+
+*  Class Membership:
+*     SelectorMap constructor.
+
+*  Description:
+*     This function creates a new SelectorMap and optionally initialises its
+*     attributes.
+
+*  Parameters:
+*     nreg
+*        The number of Regions supplied.
+*     regs
+*        An array of pointers to the Regions. Deep copies of these
+*        Regions are taken.
+*     badval
+*        The value to be returned by the forward transformation of the
+*        SelectorMap for any input positions that have a bad (AST__BAD)
+*        value on any axis.
+*     options
+*        Pointer to a null terminated string containing an optional
+*        comma-separated list of attribute assignments to be used for
+*        initialising the new SelectorMap. The syntax used is the same as for the
+*        astSet method and may include "printf" format specifiers identified
+*        by "%" symbols in the normal way.
+*     ...
+*        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 SelectorMap.
+
+*  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 SelectorMap constructor which is
+*     available via the protected interface to the SelectorMap class.  A
+*     public interface is provided by the astSelectorMapId_ 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
+*     "map1" and "map2" parameters are of type (void *) and are
+*     converted and validated within the function itself.
+*/
+
+/* Local Variables: */
+   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
+   AstSelectorMap *new;          /* Pointer to new SelectorMap */
+   AstRegion **regs;             /* Array of Region pointers */
+   int i;                        /* Region index */
+   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;
+
+/* Report an error if no Regions have been supplied. */
+   if( nreg <= 0 ) astError( AST__BDPAR, "astSelectorMap(SelectorMap): "
+                            "Bad number of Regions (%d) specified.", status, nreg );
+
+/* Otherwise create an array to hold the Region pointers. */
+   regs = astMalloc( sizeof( AstRegion * )*nreg );
+
+/* Obtain and validate pointers to the Region structures provided. */
+   if( astOK ) {
+      for( i = 0; i < nreg; i++ ) {
+         regs[ i ] = astCheckRegion( regs_void[ i ] );
+      }
+   }
+
+   if ( astOK ) {
+
+/* Initialise the SelectorMap, allocating memory and initialising the
+   virtual function table as well if necessary. */
+      new = astInitSelectorMap( NULL, sizeof( AstSelectorMap ), !class_init, &class_vtab,
+                              "SelectorMap", nreg, regs, badval );
+
+/* 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 SelectorMap'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 );
+      }
+   }
+
+/* Free memory used to hold the Regions pointers. */
+   regs = astFree( regs );
+
+/* Return a pointer to the new SelectorMap. */
+   return new;
+}
+
+AstSelectorMap *astSelectorMapId_( int nreg, void **regs_void, double badval,
+                                   const char *options, ... ) {
+/*
+*++
+*  Name:
+c     astSelectorMap
+f     AST_SELECTORMAP
+
+*  Purpose:
+*     Create a SelectorMap.
+
+*  Type:
+*     Public function.
+
+*  Synopsis:
+c     #include "selectormap.h"
+c     AstSelectorMap *astSelectorMap( int nreg, AstRegion *regs[],
+c                                     double badval, const char *options, ... )
+f     RESULT = AST_SELECTORMAP( NREG, REGS, BADVAL, OPTIONS, STATUS )
+
+*  Class Membership:
+*     SelectorMap constructor.
+
+*  Description:
+*     This function creates a new SelectorMap and optionally initialises
+*     its attributes.
+*
+*     A SelectorMap is a Mapping that identifies which Region contains
+*     a given input position.
+*
+*     A SelectorMap encapsulates a number of Regions that all have the same
+*     number of axes and represent the same coordinate Frame. The number of
+*     inputs (Nin attribute) of the SelectorMap equals the number of axes
+*     spanned by one of the encapsulated Region. All SelectorMaps have only
+*     a single output. SelectorMaps do not define an inverse transformation.
+*
+*     For each input position, the forward transformation of a SelectorMap
+*     searches through the encapsulated Regions (in the order supplied when
+*     the SelectorMap was created) until a Region is found which contains
+*     the input position. The index associated with this Region is
+*     returned as the SelectorMap output value (the index value is the
+*     position of the Region within the list of Regions supplied when the
+*     SelectorMap was created, starting at 1 for the first Region). If an
+*     input position is not contained within any Region, a value of zero is
+*     returned by the forward transformation.
+*
+*     If a compound Mapping contains a SelectorMap in series with its own
+*     inverse, the combination of the two adjacent SelectorMaps will be
+*     replaced by a UnitMap when the compound Mapping is simplified using
+c     astSimplify.
+f     AST_SIMPLIFY.
+*
+*     In practice, SelectorMaps are often used in conjunction with SwitchMaps.
+
+*  Parameters:
+c     nreg
+f     NREG = INTEGER (Given)
+*        The number of supplied Regions.
+c     regs
+f     REGS( NREG ) = INTEGER (Given)
+*        An array of pointers to the Regions. All the supplied Regions must
+*        relate to the same coordinate Frame. The number of axes in this
+*        coordinate Frame defines the number of inputs for the SelectorMap.
+c     badval
+f     BADVAL = DOUBLE PRECISION (Given)
+*        The value to be returned by the forward transformation of the
+*        SelectorMap for any input positions that have a bad (AST__BAD)
+*        value on any axis.
+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 SelectorMap. 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 SelectorMap. 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     astSelectorMap()
+f     AST_SELECTORMAP = INTEGER
+*        A pointer to the new SelectorMap.
+
+*  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 SelectorMap.
+*     - 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 astSelectorMap constructor function. It returns an ID value
+*     (instead of a true C pointer) to external users, and must be
+*     provided because astSelectorMap_ 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 "map1" and "map2" 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 astSelectorMap_ 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 */
+   AstSelectorMap *new;          /* Pointer to new SelectorMap */
+   AstRegion **regs;             /* Array of Region pointers */
+   int i;                        /* Region index */
+   va_list args;                 /* Variable argument list */
+
+   int *status;                  /* Pointer to inherited status value */
+
+/* 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;
+
+/* Report an error if no Regions have been supplied. */
+   if( nreg <= 0 ) astError( AST__BDPAR, "astSelectorMap(SelectorMap): "
+                             "Bad number of Regions (%d) specified.", status, nreg );
+
+/* Create an array to hold the Region pointers. */
+   regs = astMalloc( sizeof( AstRegion * )*nreg );
+
+/* Obtain and validate pointers to the Region structures provided. */
+   if( astOK ) {
+      for( i = 0; i < nreg; i++ ) {
+         regs[ i ] = astVerifyRegion( astMakePointer(regs_void[ i ]) );
+      }
+   }
+
+   if ( astOK ) {
+
+/* Initialise the SelectorMap, allocating memory and initialising the
+   virtual function table as well if necessary. */
+      new = astInitSelectorMap( NULL, sizeof( AstSelectorMap ), !class_init,
+                                &class_vtab, "SelectorMap", nreg, regs,
+                                badval );
+
+/* 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 SelectorMap'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 );
+      }
+   }
+
+/* Free memory used to hold the Regions pointers. */
+   regs = astFree( regs );
+
+/* Return an ID value for the new SelectorMap. */
+   return astMakeId( new );
+}
+
+AstSelectorMap *astInitSelectorMap_( void *mem, size_t size, int init,
+                                     AstSelectorMapVtab *vtab, const char *name,
+                                     int nreg, AstRegion **regs, double badval, int *status ) {
+/*
+*+
+*  Name:
+*     astInitSelectorMap
+
+*  Purpose:
+*     Initialise a SelectorMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     AstSelectorMap *astInitSelectorMap( void *mem, size_t size, int init,
+*                                         AstSelectorMapVtab *vtab, const char *name,
+*                                         int nreg, AstRegion **regs, double badval )
+
+*  Class Membership:
+*     SelectorMap initialiser.
+
+*  Description:
+*     This function is provided for use by class implementations to initialise
+*     a new SelectorMap object. It allocates memory (if necessary) to
+*     accommodate the SelectorMap plus any additional data associated with the
+*     derived class. It then initialises a SelectorMap 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 SelectorMap at the start of
+*     the memory passed via the "vtab" parameter.
+
+*  Parameters:
+*     mem
+*        A pointer to the memory in which the SelectorMap is to be initialised.
+*        This must be of sufficient size to accommodate the SelectorMap data
+*        (sizeof(SelectorMap)) 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 SelectorMap (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
+*        SelectorMap structure, so a valid value must be supplied even if not
+*        required for allocating memory.
+*     init
+*        A logical flag indicating if the SelectorMap'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 SelectorMap.
+*     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).
+*     nreg
+*        The number of Regions supplied.
+*     regs
+*        An array holdiong pointers to the Regions. Deep copies are taken
+*        of these Regions.
+*     badval
+*        The value to be returned by the forward transformation of the
+*        SelectorMap for any input positions that have a bad (AST__BAD)
+*        value on any axis.
+
+*  Returned Value:
+*     A pointer to the new SelectorMap.
+
+*  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: */
+   AstFrame *f0;                 /* Frame from first Region */
+   AstFrame *f1;                 /* Frame from current Region */
+   AstSelectorMap *new;          /* Pointer to new SelectorMap */
+   int equal;                    /* Are Frames equal? */
+   int i;                        /* Loop count */
+   int nin;                      /* No. input coordinates for SelectorMap */
+
+/* Check the global status. */
+   if ( !astOK ) return NULL;
+
+/* If necessary, initialise the virtual function table. */
+   if ( init ) astInitSelectorMapVtab( vtab, name );
+
+/* Initialise. */
+   new = NULL;
+
+/* Check that all Regions refer to the same Frame. */
+   f0 = astRegFrame( regs[ 0 ] );
+   for( i = 1; i < nreg; i++ ) {
+      f1 = astRegFrame( regs[ i ] );
+      equal = astEqual( f1, f0 );
+      f1 = astAnnul( f1 );
+
+      if( !equal ) {
+         if( astOK ) {
+            astError( AST__BADNI, "astInitSelectorMap(%s): Region "
+                      "number %d does not refer to the same coordinate "
+                      "Frame as the first Region.", status, name, i + 1 );
+         }
+      }
+   }
+
+   nin = astGetNin( regs[ 0 ] );
+   f0 = astAnnul( f0 );
+
+/* Initialise a Mapping structure (the parent class) as the first component
+   within the SelectorMap structure, allocating memory if necessary. Specify
+   the number of input and output coordinates and in which directions the
+   Mapping should be defined. */
+   if ( astOK ) {
+      new = (AstSelectorMap *) astInitMapping( mem, size, 0,
+                                             (AstMappingVtab *) vtab, name,
+                                             nin, 1, 1, 0 );
+      if ( astOK ) {
+
+/* Initialise the SelectorMap data. */
+/* -------------------------------- */
+
+/* Create an array for the Region pointers. */
+         new->reg = astMalloc( sizeof( AstRegion * )*nreg );
+
+/* Store pointers to deep copies of the Regions. */
+         if( astOK ) {
+            new->nreg = nreg;
+            for( i = 0; i < nreg; i++ ) {
+               new->reg[ i ] = astCopy( regs[ i ] );
+            }
+         } else {
+            new->nreg = 0;
+         }
+
+/* Store other items */
+         new->badval = badval;
+
+/* If an error occurred, clean up by deleting the new object. */
+         if ( !astOK ) new = astDelete( new );
+      }
+   }
+
+/* Return a pointer to the new object. */
+   return new;
+}
+
+AstSelectorMap *astLoadSelectorMap_( void *mem, size_t size,
+                                     AstSelectorMapVtab *vtab, const char *name,
+                                     AstChannel *channel, int *status ) {
+/*
+*+
+*  Name:
+*     astLoadSelectorMap
+
+*  Purpose:
+*     Load a SelectorMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "selectormap.h"
+*     AstSelectorMap *astLoadSelectorMap( void *mem, size_t size,
+*                                         AstSelectorMapVtab *vtab, const char *name,
+*                                         AstChannel *channel )
+
+*  Class Membership:
+*     SelectorMap loader.
+
+*  Description:
+*     This function is provided to load a new SelectorMap 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
+*     SelectorMap 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 SelectorMap at the start of the memory
+*     passed via the "vtab" parameter.
+
+
+*  Parameters:
+*     mem
+*        A pointer to the memory into which the SelectorMap is to be
+*        loaded.  This must be of sufficient size to accommodate the
+*        SelectorMap data (sizeof(SelectorMap)) 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 SelectorMap (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 SelectorMap 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(AstSelectorMap) is used instead.
+*     vtab
+*        Pointer to the start of the virtual function table to be
+*        associated with the new SelectorMap. If this is NULL, a pointer to
+*        the (static) virtual function table for the SelectorMap 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 "SelectorMap" is used instead.
+
+*  Returned Value:
+*     A pointer to the new SelectorMap.
+
+*  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 */
+   AstSelectorMap *new;
+   AstFrameSet *fs;
+   AstRegion *reg;
+   int i;
+   char buf[ 20 ];
+
+/* 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 SelectorMap. In this case the
+   SelectorMap belongs to this class, so supply appropriate values to be
+   passed to the parent class loader (and its parent, etc.). */
+   if ( !vtab ) {
+      size = sizeof( AstSelectorMap );
+      vtab = &class_vtab;
+      name = "SelectorMap";
+
+/* If required, initialise the virtual function table for this class. */
+      if ( !class_init ) {
+         astInitSelectorMapVtab( 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 SelectorMap. */
+   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, "SelectorMap" );
+
+/* 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. */
+
+
+/* Loop to load each Region. */
+/* ------------------------- */
+      new->reg = NULL;
+      i = 0;
+      fs = NULL;
+      while( astOK ) {
+         sprintf( buf, "reg%d", i + 1 );
+         reg = astReadObject( channel, buf, NULL );
+         if( reg ) {
+            new->reg = astGrow( new->reg, i + 1, sizeof( AstRegion *) );
+            if( astOK ) {
+               new->reg[ i ] = reg;
+
+/* All but the first Region may have a dummy FrameSet rather than the
+   correct FrameSet. The correct FrameSet will be a copy of the FrameSet
+   from the first Region. */
+               if( i == 0 ) {
+                  fs = astGetRegFS( reg );
+               } else if( astRegDummyFS( reg ) ){
+                  astSetRegFS( reg, fs );
+               }
+
+               i++;
+            }
+         } else {
+            break;
+         }
+      }
+
+      fs = astAnnul( fs );
+
+/* Number of Regions. */
+      new->nreg = i;
+
+
+/* BadVal. */
+/* ------- */
+      new->badval = astReadDouble( channel, "badval", AST__BAD );
+
+/* If an error occurred, clean up by deleting the new SelectorMap. */
+      if ( !astOK ) new = astDelete( new );
+   }
+
+/* Return the new SelectorMap 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. */
+
+
+
+