debian man page for pdpttrf

PDPTTRF(l)						   LAPACK routine (version 1.5) 						PDPTTRF(l)

NAME
       PDPTTRF - 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 PDPTTRF( N, D, E, JA, DESCA, AF, LAF, WORK, LWORK, INFO )

	   INTEGER	   INFO, JA, LAF, LWORK, N

	   INTEGER	   DESCA( * )

	   DOUBLE	   PRECISION AF( * ), D( * ), E( * ), WORK( * )

PURPOSE
       PDPTTRF	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 PDPTTRS 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 							PDPTTRF(l)