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astMapSplit
-
Split a Mapping up into parallel component Mappings
- Description:
- This function
creates a new Mapping which connects specified inputs within a
supplied Mapping to the corresponding outputs of the supplied Mapping.
This is only possible if the specified inputs correspond to some
subset of the Mapping outputs. That is, there must exist a subset of
the Mapping outputs for which each output depends only on the selected
Mapping inputs, and not on any of the inputs which have not been
selected. Also, any output which is not in this subset must not depend
on any of the selected inputs. If these conditions are not met by the
supplied Mapping, then
a NULL
Mapping pointer is returned.
- Synopsis:
- void astMapSplit( AstMapping
this, int nin, const int
in, int
out,
AstMapping 
map )
- Parameters:
-
this
-
Pointer to the Mapping to be split.
-
nin
-
The number of inputs to pick from "this".
-
in
-
Pointer to an
array holding the indices within the supplied Mapping of the inputs
which are to be picked from the Mapping.
This array should have "nin" elements.
If "Nin" is the number of inputs of the supplied Mapping, then each
element should have a value in the range 1 to Nin.
-
out
-
Pointer to an
array in which to return the indices of the outputs of the supplied
Mapping which are fed by the picked inputs. A value of one is
used to refer to the first Mapping output. The supplied array should
have a length at least equal to the number of outputs in the
supplied Mapping. The number of values stored in the array on
exit will equal the number of outputs in the returned Mapping.
The i'th element in the returned array holds the index within
the supplied Mapping which corresponds to the i'th output of
the returned Mapping.
-
map
-
Address of a location at which to return a pointer to the
returned Mapping. This Mapping will have
"nin" inputs (the number of outputs may be different to "nin"). NULL
is returned if the supplied Mapping has no subset of outputs which
depend only on the selected inputs. The returned Mapping is a
deep copy of the required parts of the supplied Mapping.
- Notes:
- If this
function
is invoked with the global error status set, or if it should fail for
any reason, then
a NULL value
will be returned for
the "map" pointer.
Next: astMapType - Get the data type of an entry in a KeyMap
Up: AST Function Descriptions
Previous: astMapSize - Get the number of entries in a KeyMap
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk
Copyright (C) 2009 Science \& Technology Facilities Council