NAME

zlagtm - perform a matrix-vector product of the form   B := alpha ∗ A ∗ X + beta ∗ B  where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be zero, one, or minus one

SYNOPSIS

SUBROUTINE ZLAGTM( TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA, B, LDB )

CHARACTER TRANS

INTEGER LDB, LDX, N, NRHS

DOUBLE PRECISION ALPHA, BETA

COMPLEX∗16 B( LDB, ∗ ), D( ∗ ), DL( ∗ ), DU( ∗ ), X( LDX, ∗ )

#include <sunperf.h>

void zlagtm(char trans, int n, int nrhs, double alpha, doublecomplex ∗dl, doublecomplex ∗d, doublecomplex ∗du, doublecomplex ∗zx, int ldx, double dbeta, doublecomplex ∗zb, int ldb) ;

PURPOSE

ZLAGTM performs a matrix-vector product of the form
 

ARGUMENTS

TRANS (input) CHARACTER
Specifies the operation applied to A. = ’N’:  No transpose, B := alpha ∗ A ∗ X + beta ∗ B
= ’T’:  Transpose,    B := alpha ∗ A∗∗T ∗ X + beta ∗ B
= ’C’:  Conjugate transpose, B := alpha ∗ A∗∗H ∗ X + beta ∗ B

N (input) INTEGER
The order of the matrix A.  N >= 0.

NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns of the matrices X and B.

ALPHA (input) DOUBLE PRECISION
The scalar alpha.  ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0.

DL (input) COMPLEX∗16 array, dimension (N-1)
The (n-1) sub-diagonal elements of T.

D (input) COMPLEX∗16 array, dimension (N)
The diagonal elements of T.

DU (input) COMPLEX∗16 array, dimension (N-1)
The (n-1) super-diagonal elements of T.

X (input) COMPLEX∗16 array, dimension (LDX,NRHS)
The N by NRHS matrix X. LDX     (input) INTEGER The leading dimension of the array X.  LDX >= max(N,1).

BETA (input) DOUBLE PRECISION
The scalar beta.  BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1.

B (input/output) COMPLEX∗16 array, dimension (LDB,NRHS)
On entry, the N by NRHS matrix B. On exit, B is overwritten by the matrix expression B := alpha ∗ A ∗ X + beta ∗ B.

LDB (input) INTEGER
The leading dimension of the array B.  LDB >= max(N,1).

SunOS 5.0  —  Last change: 10 Dec 1998