A PermMap is a MappingMapping which permutes the order of coordinates, and possibly also changes the number of coordinates, between its input and output.
In addition to permuting the coordinate order, a PermMap may also assign constant values to coordinates. This is useful when the number of coordinates is being increased as it allows fixed values to be assigned to any new ones.
For details of additional special values that may be used in this array, see the description of the "constant" parameter.
If a NULL pointer is supplied instead of an array, each input coordinate will obtain its value from the corresponding output coordinate (or will be assigned the value AST__BAD if there is no corresponding output coordinate).
For details of additional special values that may be used in this array, see the description of the "constant" parameter.
If a NULL pointer is supplied instead of an array, each output coordinate will obtain its value from the corresponding input coordinate (or will be assigned the value AST__BAD if there is no corresponding input coordinate).
Care should be taken to ensure that locations lying outside the extent of this array are not accidentally addressed. The array is not used if the "inperm" and "outperm" arrays do not contain negative values.
If a NULL pointer is supplied instead of an array, the behaviour is as if the array were of infinite length and filled with the value AST__BAD.