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A Library for Handling
World Coordinate Systems
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Description:
This routine joins a
series of points specified in the physical coordinate system of a
Plot by drawing a sequence
of geodesic curves. It is equivalent to making repeated calls to the
AST_CURVE routine
(q.v.), except that AST_POLYCURVE will generally be more efficient when drawing many
geodesic curves endtoend. A typical application of this might be in drawing contour
lines.
As with AST_CURVE, full account is taken of the Mapping between physical and graphical coordinate
systems. This includes any discontinuities and clipping established using AST_CLIP.
Invocation
CALL AST_POLYCURVE( THIS, NPOINT, NCOORD, INDIM, IN, STATUS )
Arguments
THIS =
INTEGER (Given)
Pointer to the Plot.
NPOINT = INTEGER (Given)
The number of points
between which geodesic curves are to be drawn.
NCOORD = INTEGER (Given)
The number of
coordinates being supplied for each point (i.e. the number of axes in the current
Frame of the Plot, as
given by its
Naxes attribute).
INDIM = INTEGER (Given)
The number of elements along the first
dimension of the IN array (which contains the input coordinates). This value is required so
that the coordinate values can be correctly located if they do not entirely fill this array.
The value given should not be less than NPOINT.
IN( INDIM, NCOORD ) = DOUBLE
PRECISION (Given)
A 2dimensional array giving the physical coordinates of the points
which are to be joined in sequence by geodesic curves. These should be stored such that the
value of coordinate number COORD for input point number POINT is found in element
IN(POINT,COORD).
STATUS = INTEGER (Given and Returned)
The global status.
Notes:

No curve is drawn on either side of any point which has any coordinate equal to the value
AST__BAD.

An error results if the base Frame of the Plot is not 2dimensional.

An error also results if the transformation between the current and base Frames of the Plot is not
defined (i.e. the Plot’
s TranInverse attribute is zero).
Copyright (C) 2021 East Asian Observatory
 ←Prev
 AST
A Library for Handling
World Coordinate
Systems
in Astronomy  Next→
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