man pcpbtrf (Fonctions bibliothèques) - compute a Cholesky factorization of an N-by-N complex banded symmetric positive definite distributed matrix with bandwidth BW
NAME
PCPBTRF - compute a Cholesky factorization of an N-by-N complex banded symmetric positive definite distributed matrix with bandwidth BW
SYNOPSIS
- SUBROUTINE PCPBTRF(
- UPLO, N, BW, A, JA, DESCA, AF, LAF, WORK, LWORK, INFO )
- CHARACTER UPLO
- INTEGER BW, INFO, JA, LAF, LWORK, N
- INTEGER DESCA( * )
- COMPLEX A( * ), AF( * ), WORK( * )
PURPOSE
PCPBTRF computes a Cholesky factorization
of an N-by-N complex 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 PCPBTRS 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.