PSPBTRF - compute a Cholesky factorization of an N-by-N real banded symmetric positive definite

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

       PSPBTRF 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 PSPBTRS 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.

LAPACK version 1.5                                 12 May 1997                                        PSPBTRF(l)

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

           CHARACTER       UPLO

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

           INTEGER         DESCA( * )

           REAL            A( * ), AF( * ), WORK( * )