Transform N-dimensional coordinates held in separate arrays

This function applies a Mapping to transform the coordinates of a set of
points in an arbitrary number of dimensions. It is the appropriate routine to use if
the coordinates are not purely 1- or 2-dimensional and are stored in separate
arrays, since each coordinate array is located by supplying a separate pointer to
it.

If the coordinates are stored in a single (2-dimensional) array, then the astTranN function might be more suitable.

void astTranP( AstMapping
$\ast $this, int npoint, int ncoord_in,
const double $\ast $ptr_in[], int forward,
int ncoord_out, double $\ast $ptr_out[]
)

Pointer to the Mapping to be applied.

The number
of points to be transformed.

The number of coordinates being supplied
for each input point (i.e. the number of dimensions of the space in which the input
points reside).

An array of pointers to double, with

`"`

ncoord_in`"`

elements.
Element `"`

ptr_in[coord]`"`

should point at the first element of an array of double (with
`"`

npoint`"`

elements) which contain the values of coordinate number `"`

coord`"`

for each
input (untransformed) point. The value of coordinate number `"`

coord`"`

for input point
number `"`

point`"`

is therefore given by `"`

ptr_in[coord][point]`"`

(assuming both indices
are zero-based). 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. The number of
coordinates being generated by the Mapping for each output point (i.e. the number
of dimensions of the space in which the output points reside). This need not
be the same as

`"`

ncoord_in`"`

. An array of pointers to double,
with

`"`

ncoord_out`"`

elements. Element `"`

ptr_out[coord]`"`

should point at the
first element of an array of double (with `"`

npoint`"`

elements) into which the
values of coordinate number `"`

coord`"`

for each output (transformed) point will
be written. The value of coordinate number `"`

coord`"`

for output point number
`"`

point`"`

will therefore be found in `"`

ptr_out[coord][point]`"`

. -
If the forward coordinate transformation is being applied, the Mapping supplied must have the value of

`"`

ncoord_in`"`

for its Nin attribute and the value of`"`

ncoord_out`"`

for its Nout attribute. If the inverse transformation is being applied, these values should be reversed. -
This routine is not available in the Fortran 77 interface to the AST library.

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, astTranP
becomes astTranP8. Copyright (C) 2019 East Asian Observatory