- ←Prev
- AST
A Library for Handling
World Coordinate Systems
in Astronomy - Next→
- TOC ↑
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.
Copyright (C) 2017 East Asian Observatory
- ←Prev
- AST
A Library for Handling
World
Coordinate Systems
in Astronomy - Next→
- TOC ↑