DragonFly On-Line Manual Pages

PSPBTRF(l)                             )                            PSPBTRF(l)

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

SYNOPSIS
       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( * )

PURPOSE
       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.

ScaLAPACK version 1.7           13 August 2001                      PSPBTRF(l)