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AST_NORM - Normalise a set of Frame coordinates   

Description:
This routine normalises a set of Frame coordinate values which might be unsuitable for display (e.g. may lie outside the expected range) into a set of acceptable values suitable for display.

Invocation:
CALL AST_NORM( THIS, VALUE, STATUS )

Arguments:
THIS = INTEGER (Given)
Pointer to the Frame.
VALUE( * ) = DOUBLE PRECISION (Given and Returned)
An array with one element for each Frame axis (Naxes attribute). Initially, this should contain a set of coordinate values representing a point in the space which the Frame describes. If these values lie outside the expected range for the Frame, they will be replaced with more acceptable (normalised) values. Otherwise, they will be returned unchanged.
STATUS = INTEGER (Given and Returned)
The global status.

Notes:
  • For some classes of Frame, whose coordinate values are not constrained, this function will never modify the values supplied. However, for Frames whose axes represent cyclic quantities (such as angles or positions on the sky), coordinates will typically be wrapped into an appropriate standard range, such as zero to 2*pi.
  • It is intended to be possible to put any set of coordinates into a form suitable for display by using this function to normalise them, followed by appropriate formatting (using AST_FORMAT).



next up previous
Next: AST_OFFSET - Calculate an offset along a geodesic curve
Up: AST Routine Descriptions
Previous: AST_MATRIXMAP - Create a MatrixMap

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
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