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Description:
This routine aligns a supplied WCS axis to the best-matching pixel axis of an NDF. It also
returns pixel co-ordinates corresponding to supplied WCS-axis limits, and where possible a
mapping with one input and one output that transforms current Frame co-ordinates into pixel
co-ordinates.
It first attempts to split the mapping to derive a one-to-one mapping. Failing that it
Invocation
CALL
KPG1_ASAPA( INDF, FRM, MAP, IAXIS, AXLOW, AXHIGH, PAXIS, PXLOW, PXHIGH, MAP1D, STATUS )
Arguments
INDF = INTEGER (Given)
The identifier of the NDF containing a WCS component.
FRM = INTEGER (Given)
An AST pointer to the current Frame in the NDF.
MAP = INTEGER
(Given)
The mapping from the PIXEL Frame to the current WCS Frame. This can also be a mapping
from GRID to the current Frame. In which case the returned co-ordinates and mapping apply to GRID
co-ordinates instead of PIXEL.
IAXIS = INTEGER (Given)
The index of the WCS axis in the current
Frame to be aligned.
AXLOW = DOUBLE PRECISION (Given)
Lower bound of the
WCS axis. If either AXLOW or AXHIGH is set to AST__BAD, then the whole axis range is
used.
AXHIGH = DOUBLE PRECISION (Given)
Upper bound of the WCS axis. If either
AXLOW or AXHIGH is set to AST__BAD, then the whole axis range is used.
PAXIS
= INTEGER (Returned)
The index of the pixel most closely aligned with the supplied
WCS axis.
PXLOW = DOUBLE PRECISION (Given)
Lower bound of the PIXEL axis
corresponding to the AXLOW in the WCS axis.
PXHIGH = DOUBLE PRECISION (Given)
Upper bound of the PIXEL axis corresponding to the AXHIGH in the WCS axis.
MAP1D =
INTEGER (Returned)
The mapping from the current WCS Frame to PIXEL whose input is
purely along the chosen axis (IAXIS). It is set to AST__NULL if the supplied mapping
(MAP) could not be split.
STATUS = INTEGER (Given and Returned)
The global status.
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