Retrieve the coefficient values used by a PolyMap

This function returns the coefficient values used by either the forward or inverse
transformation of a PolyMap, in the same form that they are supplied to the PolyMap
constructor.

Usually, you should call this method first with `"`

nel`"`

set to zero to determine the
number of coefficients used by the PolyMap. This allows you to allocate an array of the
correct size to hold all coefficient data. You should then call this method a second
time to get the coefficient data.

void astPolyCoeffs( AstPolyMap
$\ast $this, int forward, int
nel, double $\ast $coeffs,
int $\ast $ncoeff
)

Pointer to the original Mapping.

If non-zero, the coefficients of the forward PolyMap transformation are
returned. Otherwise the inverse transformation coefficients are returned.

The length of the supplied

`"`

coeffs`"`

array. It should be at least `"`

ncoeff$\ast $( nin
$+$ 2 )`"`

if `"`

foward`"`

is
non-zero, and `"`

ncoeff$\ast $(
nout $+$
2 )`"`

otherwise, where `"`

ncoeff`"`

is the number of coefficients to be returned. If a
value of zero is supplied, no coefficient values are returned, but the number of
coefficients used by the transformation is still returned in `"`

ncoeff`"`

. An
array in which to return the coefficients used by the requested transformation of the
PolyMap. Ignored if

`"`

nel`"`

is zero. The coefficient data is returned in the form in
which it is supplied to the PolyMap constructor. That is, each group of `"`

2
$+$ nin`"`

or `"`

2 $+$
nout`"`

adjacent elements describe a single coefficient of the forward or inverse
transformation. See the PolyMap constructor documentation for further details.
If the supplied array is too short to hold all the coefficients, trailing coefficients are excluded. If the supplied array is longer than needed to hold all the coefficients, trailing elements are filled with zeros.

The number of coefficients used by
the requested transformation. A value of zero is returned if the transformation does
not have any defining polynomials. A value is returned for this argument even if

`"`

nel`"`

is zero. Copyright (C) 2020 East Asian Observatory