AST_AXNORM

Normalise an array of axis values

Description:

This routine modifies a supplied array of axis values so that they are normalised in the manner indicated by argument OPER.

No normalisation is possible for a simple Frame and so the supplied values are returned unchanged. However, this may not be the case for specialised sub-classes of Frame. For instance, a SkyFrame has a discontinuity at zero longitude and so a longitude value can be expressed in the range [-Pi,$+$PI] or the range [0,2$\ast$PI]. See the " Applicability:" section below for details.

Invocation

CALL AST_AXNORM( THIS, AXIS, OPER, NVAL, VALUES, STATUS )

Arguments

THIS = INTEGER (Given)
Pointer to the Frame.
AXIS = INTEGER (Given)
The index of the axis to which the supplied values refer. The first axis has index 1.
OPER = INTEGER (Given)
Indicates the type of normalisation to be applied. If zero is supplied, the normalisation will be the same as that performed by routine AST_NORM. If 1 is supplied, the normalisation will be chosen automatically so that the resulting list has the smallest range.
NVAL = INTEGER (Given)
The number of points in the values array.
VALUES( NVAL ) = DOUBLE PRECISION (Given and Returned)
On entry, the axis values to be normalised. Modified on exit to hold the normalised values.
STATUS = INTEGER (Given and Returned)
The global status.

Applicability

SkyFrame
If OPER is 0, longitude values are returned in the range [0,2$\ast$PI]. If OPER is 1, longitude values are returned in either the range [0,2$\ast$PI] or [-PI,PI]. The choice is made so that that the resulting list has the smallest range. Latitude values are always returned in the range [-PI,PI].
All other classes of Frame
The supplied axis values are returned unchanged.