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astCirclePars
-
Returns the geometric parameters of an Circle
- Description:
- This function
returns the geometric parameters describing the supplied Circle.
- Synopsis:
- void astCirclePars( AstCircle
this, double
centre, double
radius,
double
p1 )
- Parameters:
-
this
-
Pointer to the Region.
-
centre
-
Pointer to an array
in which to return the coordinates of the Circle centre.
The length of this array should be no less than the number of
axes in the associated coordinate system.
-
radius
-
Returned holding the radius of the Circle, as an geodesic
distance in the associated coordinate system.
-
p1
-
Pointer to an array
in which to return the coordinates of a point on the
circumference of the Circle. The length of this array should be
no less than the number of axes in the associated coordinate system.
A NULL pointer can be supplied if the circumference position is
not needed.
- Notes:
- If the coordinate system represented by the Circle has been
changed since it was first created, the returned parameters refer
to the new (changed) coordinate system, rather than the original
coordinate system. Note however that if the transformation from
original to new coordinate system is non-linear, the shape
represented by the supplied Circle object may not be an accurate
circle.
Next: astClear - Clear attribute values for an Object
Up: AST Function Descriptions
Previous: astCircle - Create a Circle
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk
Copyright (C) 2009 Science \& Technology Facilities Council