debian man page for psgbtrf

PSGBTRF(l)						   LAPACK routine (version 1.5) 						PSGBTRF(l)

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

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

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

	   INTEGER	   DESCA( * ), IPIV( * )

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

PURPOSE
       PSGBTRF	computes a LU factorization of an N-by-N real 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 equivalent
       sequential codes. These factors cannot be used directly by users; however, they can be used in
       subsequent calls to PSGBTRS 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 							PSGBTRF(l)