astNormMap

Create a NormMap

Description:

This function creates a new NormMap and optionally initialises its attributes.

A NormMap is a Mapping which normalises coordinate values using the astNorm function of the supplied Frame. The number of inputs and outputs of a NormMap are both equal to the number of axes in the supplied Frame.

The forward and inverse transformation of a NormMap are both defined but are identical (that is, they do not form a real inverse pair in that the inverse transformation does not undo the normalisation, instead it reapplies it). However, the astSimplify function will replace neighbouring pairs of forward and inverse NormMaps by a single UnitMap (so long as the Frames encapsulated by the two NormMaps are equal - i.e. have the same class and the same attribute values). This means, for instance, that if a CmpMap contains a NormMap, the CmpMap will still cancel with its own inverse.

Synopsis

AstNormMap astNormMap( AstFrame frame, const char options, ... )

Parameters:

frame
A pointer to the Frame which is to be used to normalise the supplied axis values.
options
Pointer to a null-terminated string containing an optional comma-separated list of attribute assignments to be used for initialising the new NormMap. The syntax used is identical to that for the astSet function 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 additional 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 function (and for the C " printf" function).

Returned Value

astNormMap()
A pointer to the new NormMap.

Notes:

Status Handling

The protected interface to this function includes an extra parameter at the end of the parameter list descirbed above. This parameter is a pointer to the integer inherited status variable: " int status" .