## SYNOPSIS

- SUBROUTINE PDDTTRSV(
- UPLO, TRANS, N, NRHS, DL, D, DU, JA, DESCA, B, IB, DESCB, AF, LAF, WORK, LWORK, INFO )

- CHARACTER TRANS, UPLO

- INTEGER IB, INFO, JA, LAF, LWORK, N, NRHS

- INTEGER DESCA( * ), DESCB( * )

- DOUBLE PRECISION AF( * ), B( * ), D( * ), DL( * ), DU( * ), WORK( * )

## PURPOSE

PDDTTRSV solves a tridiagonal triangular system of linear equationsor

A(1:N, JA:JA+N-1)^T * X = B(IB:IB+N-1, 1:NRHS)

where A(1:N, JA:JA+N-1) is a tridiagonal

triangular matrix factor produced by the

Gaussian elimination code [email protected](dom_pre)TTRF

and is stored in A(1:N,JA:JA+N-1) and AF.

The matrix stored in A(1:N, JA:JA+N-1) is either

upper or lower triangular according to UPLO,

and the choice of solving A(1:N, JA:JA+N-1) or A(1:N, JA:JA+N-1)^T
is dictated by the user by the parameter TRANS.

Routine PDDTTRF MUST be called first.