NAME
PSDBTRF - compute a LU factorization of an N-by-N real banded
diagonally dominant-like distributed matrix with bandwidth BWL, BWU
SYNOPSIS
SUBROUTINE PSDBTRF( N, BWL, BWU, A, JA, DESCA, AF, LAF, WORK, LWORK,
INFO )
INTEGER BWL, BWU, INFO, JA, LAF, LWORK, N
INTEGER DESCA( * )
REAL A( * ), AF( * ), WORK( * )
PURPOSE
PSDBTRF computes a LU factorization of an N-by-N real banded diagonally
dominant-like distributed matrix with bandwidth BWL, BWU: A(1:N,
JA:JA+N-1). Reordering is used to increase parallelism in the
factorization. This reordering results in factors that are DIFFERENT
from those produced by equivalent sequential codes. These factors
cannot be used directly by users; however, they can be used in
subsequent calls to PSDBTRS to solve linear systems.
The factorization has the form
P A(1:N, JA:JA+N-1) P^T = L U
where U is a banded upper triangular matrix and L is banded lower
triangular, and P is a permutation matrix.