debian man page for pspttrf

PSPTTRF(l)						   LAPACK routine (version 1.5) 						PSPTTRF(l)

NAME
       PSPTTRF - compute a Cholesky factorization of an N-by-N real tridiagonal symmetric positive definite distributed matrix A(1:N, JA:JA+N-1)

SYNOPSIS
       SUBROUTINE PSPTTRF( N, D, E, JA, DESCA, AF, LAF, WORK, LWORK, INFO )

	   INTEGER	   INFO, JA, LAF, LWORK, N

	   INTEGER	   DESCA( * )

	   REAL 	   AF( * ), D( * ), E( * ), WORK( * )

PURPOSE
       PSPTTRF	computes  a Cholesky factorization of an N-by-N real tridiagonal symmetric positive definite distributed matrix 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 PSPTTRS to solve linear systems.

       The factorization has the form

	       P A(1:N, JA:JA+N-1) P^T = U' D U  or

	       P A(1:N, JA:JA+N-1) P^T = L D L',

       where U is a tridiagonal upper triangular matrix and L is tridiagonal lower triangular, and P is a permutation matrix.

LAPACK version 1.5						    12 May 1997 							PSPTTRF(l)