PDDTTRF(l) LAPACK routine (version 1.5) PDDTTRF(l)
NAME
PDDTTRF - compute a LU factorization of an N-by-N real tridiagonal diagonally dominant-like distributed matrix A(1:N, JA:JA+N-1)
SYNOPSIS
SUBROUTINE PDDTTRF( N, DL, D, DU, JA, DESCA, AF, LAF, WORK, LWORK, INFO )
INTEGER INFO, JA, LAF, LWORK, N
INTEGER DESCA( * )
DOUBLE PRECISION AF( * ), D( * ), DL( * ), DU( * ), WORK( * )
PURPOSE
PDDTTRF computes a LU factorization of an N-by-N real tridiagonal diagonally dominant-like distributed matrix A(1:N, JA:JA+N-1). Reorder-
ing 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 PDDTTRS to solve linear systems.
The factorization has the form
P A(1:N, JA:JA+N-1) P^T = L U
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 PDDTTRF(l)
