bionic (3) pddbtrf.3.gz

NAME

       PDDBTRF - compute a LU factorization of an N-by-N real banded diagonally dominant-like distributed matrix
       with bandwidth BWL, BWU

SYNOPSIS

       SUBROUTINE PDDBTRF( N, BWL, BWU, A, JA, DESCA, AF, LAF, WORK, LWORK, INFO )

           INTEGER         BWL, BWU, INFO, JA, LAF, LWORK, N

           INTEGER         DESCA( * )

           DOUBLE          PRECISION A( * ), AF( * ), WORK( * )

PURPOSE

       PDDBTRF 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 PDDBTRS 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.