debian man page for pcgbtrf

PCGBTRF(l)						   LAPACK routine (version 1.5) 						PCGBTRF(l)

NAME
       PCGBTRF - compute a LU factorization of an N-by-N complex banded distributed matrix with bandwidth BWL, BWU

SYNOPSIS
       SUBROUTINE PCGBTRF( N, BWL, BWU, A, JA, DESCA, IPIV, AF, LAF, WORK, LWORK, INFO )

	   INTEGER	   BWL, BWU, INFO, JA, LAF, LWORK, N

	   INTEGER	   DESCA( * ), IPIV( * )

	   COMPLEX	   A( * ), AF( * ), WORK( * )

PURPOSE
       PCGBTRF	computes a LU factorization of an N-by-N complex banded distributed matrix with bandwidth BWL, BWU: 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 equiva-
       lent sequential codes. These factors cannot be used directly by users; however, they can be used in
       subsequent calls to PCGBTRS to solve linear systems.

       The factorization has the form

	       P A(1:N, JA:JA+N-1) Q = L U

       where U is a banded upper triangular matrix and L is banded lower triangular, and P and Q are permutation matrices.
       The matrix Q represents reordering of columns
       for parallelism's sake, while P represents
       reordering of rows for numerical stability using
       classic partial pivoting.

LAPACK version 1.5						    12 May 1997 							PCGBTRF(l)