AST_NORM

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AST_NORM

Normalise a set of Frame coordinates representing one point

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.
The NormMap class is a Mapping which can be used to normalise a set of points using the AST_NORM routine of a specified Frame.
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).

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AST
A Library for Handling
World Coordinate Systems
in Astronomy
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