PDDTTRF(3)    ScaLAPACK routine of NEC Numeric Library Collection   PDDTTRF(3)



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 routine               31 October 2017                     PDDTTRF(3)