PDPTTRF(l) ) PDPTTRF(l)NAME
PDPTTRF - compute a Cholesky factorization of an N-by-N real tridiago‐
nal 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.
ScaLAPACK version 1.7 13 August 2001 PDPTTRF(l)
