PDDTTRF(l) ) 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 diag‐
onally dominant-like 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; how‐
ever, 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.
ScaLAPACK version 1.7 13 August 2001 PDDTTRF(l)
