NAME

       PDPBTRF  -  compute  a  Cholesky factorization of an N-by-N real banded symmetric positive
       definite distributed matrix with bandwidth BW

SYNOPSIS

       SUBROUTINE PDPBTRF( UPLO, N, BW, A, JA, DESCA, AF, LAF, WORK, LWORK, INFO )

           CHARACTER       UPLO

           INTEGER         BW, INFO, JA, LAF, LWORK, N

           INTEGER         DESCA( * )

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

PURPOSE

       PDPBTRF computes a Cholesky factorization of an  N-by-N  real  banded  symmetric  positive
       definite  distributed  matrix with bandwidth BW: 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 PDPBTRS to solve linear systems.

       The factorization has the form

               P A(1:N, JA:JA+N-1) P^T = U' U ,  if UPLO = 'U', or

               P A(1:N, JA:JA+N-1) P^T = L L', if UPLO = 'L'

       where U is a banded upper triangular matrix and L is banded lower triangular, and P  is  a
       permutation matrix.