astAxNorm

Normalise an array of axis values

Description:

This function modifies a supplied array of axis values so that they are normalised in the manner indicated by parameter " 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 [0,2PI]. See the " Applicability:" section below for details.

Synopsis

void astAxNorm( AstFrame this, int axis, int oper, int nval, double values, int status )

Parameters:

this
Pointer to the Frame.
axis
The index of the axis to which the supplied values refer. The first axis has index 1.
oper
Indicates the type of normalisation to be applied. If zero is supplied, the normalisation will be the same as that performed by function astNorm. If 1 is supplied, the normalisation will be chosen automatically so that the resulting list has the smallest range.
nval
The number of points in the values array.
values
On entry, the axis values to be normalised. Modified on exit to hold the normalised values.

Applicability

SkyFrame
If " oper" is 0, longitude values are returned in the range [0,2PI]. If " oper" is 1, longitude values are returned in either the range [0,2PI] 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.