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A Library for Handling
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AST_ZOOMMAP
Create a ZoomMap
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).
Invocation
RESULT = AST_ZOOMMAP( NCOORD, ZOOM,
OPTIONS, STATUS )
Arguments
NCOORD = INTEGER (Given)
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 = DOUBLE PRECISION (Given)
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 = CHARACTER
∗ (
∗ )
(Given)
A character 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
AST_SET routine.
STATUS = INTEGER (Given and Returned)
The global status.
Returned Value
AST_ZOOMMAP = INTEGER
A pointer to the new ZoomMap.
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"
.
Copyright (C) 2021 East Asian Observatory
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A Library for Handling
World Coordinate
Systems
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