AST_TRAN2

Transform 2-dimensional coordinates

Description:

This routine applies a Mapping to transform the coordinates of a set of points in two dimensions.

Invocation

CALL AST_TRAN2( THIS, NPOINT, XIN, YIN, FORWARD, XOUT, YOUT, STATUS )

Arguments

THIS = INTEGER (Given)
Pointer to the Mapping to be applied.
NPOINT = INTEGER (Given)
The number of points to be transformed.
XIN( NPOINT ) = DOUBLE PRECISION (Given)
An array of X-coordinate values for the input (untransformed) points.
YIN( NPOINT ) = DOUBLE PRECISION (Given)
An array of Y-coordinate values for the input (untransformed) points.
FORWARD = LOGICAL (Given)
A .TRUE. value indicates that the Mapping’ s forward coordinate transformation is to be applied, while a .FALSE. value indicates that the inverse transformation should be used.
XOUT( NPOINT ) = DOUBLE PRECISION (Returned)
An array into which the X-coordinates of the output (transformed) points will be written.
YOUT( NPOINT ) = DOUBLE PRECISION (Returned)
An array into which the Y-coordinates of the output (transformed) points will be written.
STATUS = INTEGER (Given and Returned)
The global status.

Notes:

Handling of Huge Pixel Arrays

If the number of points to be transformed exceeds the largest value that can be represented by a 4-byte integer, then the alternative " 8-byte" interface for this function should be used. This alternative interface uses 8 byte integer arguments (instead of 4-byte). Specifically, the argument NPOINT is changed from type INTEGER to type INTEGER∗8. The function name is changed by appending the digit " 8" to the name. Thus, AST_TRAN2 becomes AST_TRAN28.
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