upgrade AST

1 files changed, 1425 insertions, 0 deletions

diff --git a/ast/unitmap.c b/ast/unitmap.c
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+++ b/ast/unitmap.c
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+/*
+*class++
+*  Name:
+*     UnitMap
+
+*  Purpose:
+*     Unit (null) Mapping.
+
+*  Constructor Function:
+c     astUnitMap
+f     AST_UNITMAP
+
+*  Description:
+*     A UnitMap is a unit (null) Mapping that has no effect on the
+*     coordinates supplied to it. They are simply copied. This can be
+*     useful if a Mapping is required (e.g. to pass to another
+c     function) but you do not want it to have any effect.
+f     routine) but you do not want it to have any effect.
+*     The Nin and Nout attributes of a UnitMap are always equal and
+*     are specified when it is created.
+
+*  Inheritance:
+*     The UnitMap class inherits from the Mapping class.
+
+*  Attributes:
+*     The UnitMap class does not define any new attributes beyond
+*     those which are applicable to all Mappings.
+
+*  Functions:
+c     The UnitMap class does not define any new functions beyond those
+f     The UnitMap 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 (JAC, Hawaii)
+
+*  History:
+*     7-FEB-1996 (RFWS):
+*        Original version.
+*     13-DEC-1996 (RFWS):
+*        Over-ride the astMapMerge method.
+*     8-JAN-2003 (DSB):
+*        Changed private InitVtab method to protected astInitUnitMapVtab
+*        method.
+*     10-MAY-2006 (DSB):
+*        Override astEqual.
+*     17-FEB-2012 (DSB):
+*        In Transform, do not copy the coordinate values if the input and
+*        output array are the same.
+*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 UnitMap
+
+/* Include files. */
+/* ============== */
+/* Interface definitions. */
+/* ---------------------- */
+
+#include "globals.h"             /* Thread-safe global data access */
+#include "error.h"               /* Error reporting facilities */
+#include "object.h"              /* Base Object class */
+#include "memory.h"              /* AST memory management */
+#include "pointset.h"            /* Sets of points/coordinates */
+#include "mapping.h"             /* Coordinate mappings (parent class) */
+#include "unitmap.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>
+
+/* 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 * );
+
+
+#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(UnitMap)
+
+/* Define macros for accessing each item of thread specific global data. */
+#define class_init astGLOBAL(UnitMap,Class_Init)
+#define class_vtab astGLOBAL(UnitMap,Class_Vtab)
+
+
+#include <pthread.h>
+
+
+#else
+
+
+/* Define the class virtual function table and its initialisation flag
+   as static variables. */
+static AstUnitMapVtab 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. */
+AstUnitMap *astUnitMapId_( int, const char *, ... );
+
+/* Prototypes for Private Member Functions. */
+/* ======================================== */
+static AstPointSet *Transform( AstMapping *, AstPointSet *, int, AstPointSet *, 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 void Dump( AstObject *, AstChannel *, int * );
+
+/* Member functions. */
+/* ================= */
+static int Equal( AstObject *this_object, AstObject *that_object, int *status ) {
+/*
+*  Name:
+*     Equal
+
+*  Purpose:
+*     Test if two UnitMaps are equivalent.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     int Equal( AstObject *this, AstObject *that, int *status )
+
+*  Class Membership:
+*     UnitMap 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 UnitMaps are equivalent.
+
+*  Parameters:
+*     this
+*        Pointer to the first Object (a UnitMap).
+*     that
+*        Pointer to the second Object.
+*     status
+*        Pointer to the inherited status variable.
+
+*  Returned Value:
+*     One if the UnitMaps 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: */
+   AstUnitMap *that;
+   AstUnitMap *this;
+   int result;
+
+/* Initialise. */
+   result = 0;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* Obtain pointers to the two UnitMap structures. */
+   this = (AstUnitMap *) this_object;
+   that = (AstUnitMap *) that_object;
+
+/* Check the second object is a UnitMap. We know the first is a
+   UnitMap since we have arrived at this implementation of the virtual
+   function. */
+   if( astIsAUnitMap( that ) ) {
+
+/* Get the number of inputs check they are the same for both. */
+      result = ( astGetNin( this ) == astGetNin( that ) );
+
+   }
+
+/* If an error occurred, clear the result value. */
+   if ( !astOK ) result = 0;
+
+/* 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 UnitMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "mapping.h"
+*     void GetIsLinear( AstMapping *this, int *status )
+
+*  Class Membership:
+*     UnitMap 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 UnitMap.
+*     status
+*        Pointer to the inherited status variable.
+*/
+   return 1;
+}
+
+void astInitUnitMapVtab_(  AstUnitMapVtab *vtab, const char *name, int *status ) {
+/*
+*+
+*  Name:
+*     astInitUnitMapVtab
+
+*  Purpose:
+*     Initialise a virtual function table for a UnitMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     void astInitUnitMapVtab( AstUnitMapVtab *vtab, const char *name )
+
+*  Class Membership:
+*     UnitMap vtab initialiser.
+
+*  Description:
+*     This function initialises the component of a virtual function
+*     table which is used by the UnitMap 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 astIsAUnitMap) 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_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, "UnitMap", "Unit (null) 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) );
+   }
+}
+
+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 UnitMap.
+
+*  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:
+*     UnitMap 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 UnitMap 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 UnitMap 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 UnitMap which is to be merged with
+*        its neighbours. This should be a cloned copy of the UnitMap
+*        pointer contained in the array element "(*map_list)[where]"
+*        (see below). This pointer will not be annulled, and the
+*        UnitMap it identifies will not be modified by this function.
+*     where
+*        Index in the "*map_list" array (below) at which the pointer
+*        to the nominated UnitMap 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;              /* Pointer to replacement UnitMap */
+   const char *class;            /* Pointer to Mapping class string */
+   int i1;                       /* Index of first UnitMap to merge */
+   int i2;                       /* Index of last UnitMap to merge */
+   int i;                        /* Loop counter for Mappings */
+   int ngone;                    /* Number of UnitMaps eliminated */
+   int nin;                      /* Number of coordinates for UnitMap */
+   int result;                   /* Result value to return */
+
+/* Initialise. */
+   result = -1;
+
+/* Check the global error status. */
+   if ( !astOK ) return result;
+
+/* If the Mapping sequence consists of a single UnitMap, simply check
+   if the asociated Invert flag is set, and clear it if necessary. */
+   if ( *nmap == 1 ) {
+      if ( ( *invert_list )[ 0 ] ) {
+         ( *invert_list )[ 0 ] = 0;
+
+/* Note if the Mapping sequence was modified. */
+         result = 0;
+      }
+
+/* In series. */
+/* ========== */
+/* If a UnitMap occurs in series with any other Mapping, it can simply
+   be eliminated, so annul its Mapping pointer. */
+   } else if ( *nmap > 1 ) {
+      if ( series ) {
+         ( *map_list )[ where ] = astAnnul( ( *map_list )[ where ] );
+
+/* Loop to move any following pointers and their Invert flags down in
+   the array to fill the gap, and clear the vacated elements at the
+   end of the arrays. */
+         for ( i = where + 1; i < *nmap; i++ ) {
+            ( *map_list )[ i - 1 ] = ( *map_list )[ i ];
+            ( *invert_list )[ i - 1 ] = ( *invert_list )[ i ];
+         }
+         ( *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;
+
+/* In parallel. */
+/* ============ */
+/* If a UnitMap occurs in parallel with other Mappings, it can be
+   merged with any UnitMaps on either side of itself. */
+      } else {
+
+/* Initialise indices to identify any adjacent UnitMaps and the number
+   of coordinates to be handled by the replacement. */
+         i1 = i2 = where;
+         nin = astGetNin( ( *map_list )[ where ] );
+
+/* Loop to inspect earlier Mappings, obtaining the Mapping Class name
+   and checking it is "UnitMap". Quit looping as soon as any other
+   class of Mapping is found. */
+         while ( i1 - 1 >= 0 ) {
+            class = astGetClass( ( *map_list )[ i1 - 1 ] );
+            if ( !astOK || strcmp( class, "UnitMap" ) ) break;
+
+/* Update the index of the earliest UnitMap that is to be merged and
+   increment the total number of coordinates involved. */
+            i1--;
+            nin += astGetNin( ( *map_list )[ i1 ] );
+         }
+
+/* Repeat the above process to inspect any later Mappings in the
+   sequence. */
+         while ( i2 + 1 < *nmap ) {
+            class = astGetClass( ( *map_list )[ i2 + 1 ] );
+            if ( !astOK || strcmp( class, "UnitMap" ) ) break;
+            i2++;
+            nin += astGetNin( ( *map_list )[ i2 ] );
+         }
+
+/* Calculate the net number of Mappings that can be removed from the
+   sequence and check if this is zero, meaning that there were no
+   adjacent UnitMaps to merge with. */
+         if ( astOK ) {
+            ngone = i2 - i1;
+            if ( !ngone ) {
+
+/* If so, simply check if the nominated UnitMap's Invert flag is set,
+   and clear it if necessary. */
+               if ( ( *invert_list )[ where ] ) {
+                  ( *invert_list )[ where ] = 0;
+
+/* Note if the Mapping sequence was modified. */
+                  result = where;
+               }
+
+/* If UnitMaps can be merged, create the replacement UnitMap. */
+            } else {
+               new = (AstMapping *) astUnitMap( nin, "", status );
+               if ( astOK ) {
+
+/* Annul the pointers to all the UnitMaps that are being replaced. */
+                  for ( i = i1; i <= i2; i++ ) {
+                     ( *map_list )[ i ] = astAnnul( ( *map_list )[ i ] );
+                  }
+
+/* Insert the new pointer and the associated Invert flag. */
+                  ( *map_list )[ i1 ] = new;
+                  ( *invert_list )[ i1 ] = 0;
+
+/* Loop to close the resulting gap by moving subsequent elements down
+   in the arrays. */
+                  for ( i = i2 + 1; i < *nmap; i++ ) {
+                     ( *map_list )[ i - ngone ] = ( *map_list )[ i ];
+                     ( *invert_list )[ i - ngone ] = ( *invert_list )[ i ];
+                  }
+
+/* Clear the vacated elements at the end. */
+                  for ( i = *nmap - ngone; i < *nmap; i++ ) {
+                     ( *map_list )[ i ] = NULL;
+                     ( *invert_list )[ i ] = 0;
+                  }
+
+/* Decrement the Mapping count and return the index of the first
+   modified element. */
+                  ( *nmap ) -= ngone;
+                  result = i1;
+               }
+            }
+         }
+      }
+   }
+
+/* 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
+*     UnitMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     int *MapSplit( AstMapping *this, int nin, const int *in, AstMapping **map, int *status )
+
+*  Class Membership:
+*     UnitMap 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 UnitMap. This is only possible if the specified inputs
+*     correspond to some subset of the UnitMap outputs. That is, there
+*     must exist a subset of the UnitMap outputs for which each output
+*     depends only on the selected UnitMap inputs, and not on any of the
+*     inputs which have not been selected. If this condition is not met
+*     by the supplied UnitMap, then a NULL Mapping is returned.
+
+*  Parameters:
+*     this
+*        Pointer to the UnitMap to be split (the UnitMap 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 UnitMap, 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 UnitMap 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 UnitMap. 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: */
+   AstUnitMap *this;          /* Pointer to UnitMap 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 UnitMap structure. */
+   this = (AstUnitMap *) this_map;
+
+/* Allocate memory for the returned array and create a UnitMap with the
+   required number of axes. */
+   result = astMalloc( sizeof( int )*(size_t) nin );
+   *map = (AstMapping *) astUnitMap( nin, "", status );
+
+/* 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 "unitmap.h"
+*     result = Rate( AstMapping *this, double *at, int ax1, int ax2, int *status )
+
+*  Class Membership:
+*     UnitMap 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.
+
+*/
+
+   return ( ax1 == ax2 ) ? 1.0 : 0.0;
+}
+
+static AstPointSet *Transform( AstMapping *this, AstPointSet *in,
+                               int forward, AstPointSet *out, int *status ) {
+/*
+*  Name:
+*     Transform
+
+*  Purpose:
+*     Apply a UnitMap to transform a set of points.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     AstPointSet *Transform( AstMapping *this, AstPointSet *in,
+*                             int forward, AstPointSet *out, int *status )
+
+*  Class Membership:
+*     UnitMap member function (over-rides the astTransform method inherited
+*     from the Mapping class).
+
+*  Description:
+*     This function takes a UnitMap and a set of points encapsulated in a
+*     PointSet and transforms the points so as to perform the identity
+*     transformation (i.e. simply copies the coordinate values).
+
+*  Parameters:
+*     this
+*        Pointer to the UnitMap.
+*     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. In this case, both transformations are equivalent.
+*     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 UnitMap 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 */
+   AstUnitMap *map;              /* Pointer to UnitMap to be applied */
+   double **ptr_in;              /* Pointer to input coordinate data */
+   double **ptr_out;             /* Pointer to output coordinate data */
+   int coord;                    /* Loop counter for coordinates */
+   int ncoord_in;                /* Number of coordinates per input point */
+   int npoint;                   /* Number of points */
+
+/* Check the global error status. */
+   if ( !astOK ) return NULL;
+
+/* Obtain a pointer to the UnitMap. */
+   map = (AstUnitMap *) 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
+   coordinate copy 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 );
+
+/* We need not determine whether to apply the forward or inverse
+   transformation, as they are both the same. */
+
+/* Copy the coordinate values. */
+/* --------------------------- */
+   if ( astOK ) {
+
+/* Loop to copy the values for each coordinate. Use a memory copy for speed.
+   Do not do the copy if the input and output arrays are the same. */
+      for ( coord = 0; coord < ncoord_in; coord++ ) {
+         if( ptr_out[ coord ] != ptr_in[ coord ] ) {
+            (void) memcpy( (void *) ptr_out[ coord ],
+                           (const void *) ptr_in[ coord ],
+                           sizeof( double ) * (size_t) npoint );
+         }
+      }
+   }
+
+/* Return a pointer to the output PointSet. */
+   return result;
+}
+
+/* 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 UnitMap 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 UnitMap class to an output Channel.
+
+*  Parameters:
+*     this
+*        Pointer to the UnitMap 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: */
+   AstUnitMap *this;             /* Pointer to the UnitMap structure */
+
+/* Check the global error status. */
+   if ( !astOK ) return;
+
+/* Obtain a pointer to the UnitMap structure. */
+   this = (AstUnitMap *) this_object;
+
+/* Write out values representing the instance variables for the
+   UnitMap 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. */
+
+/* There are no values to write, so return without further action. */
+}
+
+/* Standard class functions. */
+/* ========================= */
+/* Implement the astIsAUnitMap and astCheckUnitMap functions using the macros
+   defined for this purpose in the "object.h" header file. */
+astMAKE_ISA(UnitMap,Mapping)
+astMAKE_CHECK(UnitMap)
+
+AstUnitMap *astUnitMap_( int ncoord, const char *options, int *status, ...) {
+/*
+*++
+*  Name:
+c     astUnitMap
+f     AST_UNITMAP
+
+*  Purpose:
+*     Create a UnitMap.
+
+*  Type:
+*     Public function.
+
+*  Synopsis:
+c     #include "unitmap.h"
+c     AstUnitMap *astUnitMap( int ncoord, const char *options, ... )
+f     RESULT = AST_UNITMAP( NCOORD, OPTIONS, STATUS )
+
+*  Class Membership:
+*     UnitMap constructor.
+
+*  Description:
+*     This function creates a new UnitMap and optionally initialises
+*     its attributes.
+*
+*     A UnitMap is a unit (null) Mapping that has no effect on the
+*     coordinates supplied to it. They are simply copied. This can be
+*     useful if a Mapping is required (e.g. to pass to another
+c     function) but you do not want it to have any effect.
+f     routine) but you do not want it to have any effect.
+
+*  Parameters:
+c     ncoord
+f     NCOORD = INTEGER (Given)
+*        The number of input and output coordinates (these numbers are
+*        necessarily the same).
+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 UnitMap. 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 UnitMap. 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     astUnitMap()
+f     AST_UNITMAP = INTEGER
+*        A pointer to the new UnitMap.
+
+*  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.
+*--
+*/
+
+/* Local Variables: */
+   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
+   AstUnitMap *new;              /* Pointer to new UnitMap */
+   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 UnitMap, allocating memory and initialising the
+   virtual function table as well if necessary. */
+   new = astInitUnitMap( NULL, sizeof( AstUnitMap ), !class_init, &class_vtab,
+                         "UnitMap", ncoord );
+
+/* 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
+   UnitMap'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 UnitMap. */
+   return new;
+}
+
+AstUnitMap *astUnitMapId_( int ncoord, const char *options, ... ) {
+/*
+*  Name:
+*     astUnitMapId_
+
+*  Purpose:
+*     Create a UnitMap.
+
+*  Type:
+*     Private function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     AstUnitMap *astUnitMapId_( int ncoord, const char *options, ... )
+
+*  Class Membership:
+*     UnitMap constructor.
+
+*  Description:
+*     This function implements the external (public) interface to the
+*     astUnitMap constructor function. It returns an ID value (instead
+*     of a true C pointer) to external users, and must be provided
+*     because astUnitMap_ 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 astUnitMap_ 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 astUnitMap_.
+
+*  Returned Value:
+*     The ID value associated with the new UnitMap.
+*/
+
+/* Local Variables: */
+   astDECLARE_GLOBALS            /* Pointer to thread-specific global data */
+   AstUnitMap *new;              /* Pointer to new UnitMap */
+   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 UnitMap, allocating memory and initialising the
+   virtual function table as well if necessary. */
+   new = astInitUnitMap( NULL, sizeof( AstUnitMap ), !class_init, &class_vtab,
+                         "UnitMap", ncoord );
+
+/* 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
+   UnitMap'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 UnitMap. */
+   return astMakeId( new );
+}
+
+AstUnitMap *astInitUnitMap_( void *mem, size_t size, int init,
+                             AstUnitMapVtab *vtab, const char *name,
+                             int ncoord, int *status ) {
+/*
+*+
+*  Name:
+*     astInitUnitMap
+
+*  Purpose:
+*     Initialise a UnitMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     AstUnitMap *astInitUnitMap( void *mem, size_t size, int init,
+*                                 AstUnitMapVtab *vtab, const char *name,
+*                                 int ncoord )
+
+*  Class Membership:
+*     UnitMap initialiser.
+
+*  Description:
+*     This function is provided for use by class implementations to initialise
+*     a new UnitMap object. It allocates memory (if necessary) to accommodate
+*     the UnitMap plus any additional data associated with the derived class.
+*     It then initialises a UnitMap 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 UnitMap at the start of the memory passed via the
+*     "vtab" parameter.
+
+*  Parameters:
+*     mem
+*        A pointer to the memory in which the UnitMap is to be initialised.
+*        This must be of sufficient size to accommodate the UnitMap data
+*        (sizeof(UnitMap)) 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 UnitMap (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 UnitMap
+*        structure, so a valid value must be supplied even if not required for
+*        allocating memory.
+*     init
+*        A logical flag indicating if the UnitMap'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 UnitMap.
+*     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).
+*     ncoord
+*        The number of coordinate values per point.
+
+*  Returned Value:
+*     A pointer to the new UnitMap.
+
+*  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: */
+   AstUnitMap *new;              /* Pointer to new UnitMap */
+
+/* Check the global status. */
+   if ( !astOK ) return NULL;
+
+/* If necessary, initialise the virtual function table. */
+   if ( init ) astInitUnitMapVtab( vtab, name );
+
+/* Initialise. */
+   new = NULL;
+
+/* Initialise a Mapping structure (the parent class) as the first component
+   within the UnitMap structure, allocating memory if necessary. Specify that
+   the Mapping should be defined in both the forward and inverse directions. */
+   new = (AstUnitMap *) astInitMapping( mem, size, 0,
+                                        (AstMappingVtab *) vtab, name,
+                                        ncoord, ncoord, 1, 1 );
+
+      if ( astOK ) {
+
+/* Initialise the UnitMap data. */
+/* ---------------------------- */
+/* There is nothing else to store. */
+
+/* If an error occurred, clean up by deleting the new object (if any other
+   resources had been allocated, we would free these first). */
+      if ( !astOK ) new = astDelete( new );
+   }
+
+/* Return a pointer to the new object. */
+   return new;
+}
+
+AstUnitMap *astLoadUnitMap_( void *mem, size_t size,
+                             AstUnitMapVtab *vtab, const char *name,
+                             AstChannel *channel, int *status ) {
+/*
+*+
+*  Name:
+*     astLoadUnitMap
+
+*  Purpose:
+*     Load a UnitMap.
+
+*  Type:
+*     Protected function.
+
+*  Synopsis:
+*     #include "unitmap.h"
+*     AstUnitMap *astLoadUnitMap( void *mem, size_t size,
+*                                 AstUnitMapVtab *vtab, const char *name,
+*                                 AstChannel *channel )
+
+*  Class Membership:
+*     UnitMap loader.
+
+*  Description:
+*     This function is provided to load a new UnitMap 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
+*     UnitMap 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 UnitMap at the start of the memory
+*     passed via the "vtab" parameter.
+
+
+*  Parameters:
+*     mem
+*        A pointer to the memory into which the UnitMap is to be
+*        loaded.  This must be of sufficient size to accommodate the
+*        UnitMap data (sizeof(UnitMap)) 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 UnitMap (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 UnitMap 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(AstUnitMap) is used instead.
+*     vtab
+*        Pointer to the start of the virtual function table to be
+*        associated with the new UnitMap. If this is NULL, a pointer
+*        to the (static) virtual function table for the UnitMap 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 "UnitMap" is used instead.
+
+*  Returned Value:
+*     A pointer to the new UnitMap.
+
+*  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 */
+   AstUnitMap *new;              /* Pointer to the new UnitMap */
+
+/* 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 UnitMap. In this case the
+   UnitMap belongs to this class, so supply appropriate values to be
+   passed to the parent class loader (and its parent, etc.). */
+   if ( !vtab ) {
+      size = sizeof( AstUnitMap );
+      vtab = &class_vtab;
+      name = "UnitMap";
+
+/* If required, initialise the virtual function table for this class. */
+      if ( !class_init ) {
+         astInitUnitMapVtab( 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 UnitMap. */
+   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, "UnitMap" );
+
+/* 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. */
+
+/* There are no values to read. */
+/* ---------------------------- */
+
+/* If an error occurred, clean up by deleting the new UnitMap. */
+      if ( !astOK ) new = astDelete( new );
+   }
+
+/* Return the new UnitMap 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. */
+
+/* There are none of these. */
+
+
+
+