Transform 2-dimensional coordinates

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

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

Pointer to the Mapping to be applied.

The number of points
to be transformed.

An array of X-coordinate
values for the input (untransformed) points.

An
array of Y-coordinate values for the input (untransformed) points.

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. An array into which the X-coordinates of the
output (transformed) points will be written.

An array into which the Y-coordinates of the output (transformed) points will
be written.

The global status.

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$\ast $8.
The function name is changed by appending the digit `"`

8`"`

to the name. Thus, AST_TRAN2 becomes
AST_TRAN28. Copyright (C) 2021 East Asian Observatory