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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.