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- Description:
This function creates a new ZoomMap and optionally initialises its
attributes.
A ZoomMap is a Mapping which "zooms" a set of points about the
origin by multiplying all coordinate values by the same scale
factor (the inverse transformation is performed by dividing by
this scale factor).
- Synopsis:
AstZoomMap *astZoomMap( int ncoord, double zoom,
const char *options, ... )
- Parameters:
-
ncoord
-
The number of coordinate values for each point to be
transformed (i.e. the number of dimensions of the space in
which the points will reside). The same number is applicable
to both input and output points.
-
zoom
-
Initial scale factor by which coordinate values should be
multiplied (by the forward transformation) or divided (by the
inverse transformation). This factor may subsequently be
changed via the ZoomMap's Zoom attribute. It may be positive
or negative, but should not be zero.
-
options
-
Pointer to a null-terminated string containing an optional
comma-separated list of attribute assignments to be used for
initialising the new ZoomMap. 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:
-
astZoomMap()
-
A pointer to the new ZoomMap.
- Notes:
-
A null Object pointer (AST__NULL) will be returned if this
function is invoked with the AST error status set, or if it
should fail for any reason.
Next: AST Attribute Descriptions
Up: AST Function Descriptions
Previous: astWrite - Write an Object to a Channel
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
30th April 2003
E-mail:ussc@star.rl.ac.uk
Copyright (C) 2003 Central Laboratory of the Research Councils