DragonFly On-Line Manual Pages

PDDBTRF(l)                             )                            PDDBTRF(l)

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.

ScaLAPACK version 1.7           13 August 2001                      PDDBTRF(l)