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A Library for Handling
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Description:
This function finds the angle, as seen from point
A, between the positive direction of a specified axis, and the geodesic
curve joining point A to point B.
Synopsis
double astAxAngle( AstFrame
$\ast $this,
const double a[], const double b[], int axis )
Parameters:
this
a
An array of double, with one element for each Frame axis (
Naxes
attribute) containing the coordinates of the first point.
b
An array of double,
with one element for each Frame axis (Naxes attribute) containing the coordinates of
the second point.
axis
The number of the Frame axis from which the angle is to be
measured (axis numbering starts at 1 for the first axis).
Returned Value
astAxAngle
The angle in radians, from the positive direction of the specified
axis, to the line AB. If the Frame is 2dimensional, it will be in the range
[PI/2,$+$PI/2],
and positive rotation is in the same sense as rotation from the positive direction of
axis 2 to the positive direction of axis 1. If the Frame has more than 2 axes, a
positive value will always be returned in the range zero to PI.
Notes:

The geodesic curve used by this function is the path of shortest distance between two
points, as defined by the astDistance function.

This function will return "
bad"
coordinate values (AST__BAD) if any of the input
coordinates has this value, or if the require position angle is undefined.
Copyright (C) 2021 East Asian Observatory
 ←Prev
 AST
A Library for Handling
World
Coordinate Systems
in Astronomy  Next→
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