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.