allocates a DOUBLEMASK representing the LU decomposition of the matrix in
and gives it the filename member
solves the system of linear equations (SLE) Ax=b, where matrix A has already
been decomposed into LU form in DOUBLEMASK
Input vector b is in
and is overwritten with output vector x.
is unaltered by
and can be used again to solve a different SLE containing matrix A.
The scale and offset members of
are ignored. If they are not set to 1.0 and zero respectively, you must first
To understand the decomposition A=LU, see Press et al. (1992). For the exact
format used to represent the matrices L and U in
see the acompanying source code.
is singular (non-invertible), or close to singular then
will fail, calling
returns a pointer to the new DOUBLEMASK, or NULL on error.