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 sym‐
metric positive definite distributed matrix with bandwidth BW: A(1:N,
JA:JA+N-1). Reordering is used to increase parallelism in the factor‐
ization. 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 tri‐
angular, and P is a permutation matrix.
ScaLAPACK version 1.7 13 August 2001 PSPBTRF(l)
