Transform 2-dimensional coordinates

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

void astTran2( AstMapping
$\ast $this,
int npoint, const double xin[], const double yin[], int forward, double xout[], double
yout[] )

Pointer to the Mapping to be applied.

The
number of points to be transformed.

An array of

`"`

npoint`"`

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

`"`

npoint`"`

Y-coordinate
values for the input (untransformed) points. A non-zero value indicates
that the Mapping

`’`

s forward coordinate transformation is to be applied, while a zero
value indicates that the inverse transformation should be used. An array
(with

`"`

npoint`"`

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

`"`

npoint`"`

elements) into which the
Y-coordinates of the output (transformed) points will be written. 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 `"`

int`"`

to type `"`

int64_t`"`

(defined in header file stdint.h). The
function name is changed by appending the digit `"`

8`"`

to the name. Thus, astTran2
becomes astTran28 Copyright (C) 2021 East Asian Observatory