NAME

clagtm - 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 CLAGTM( TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA, B, LDB )

CHARACTER TRANS

INTEGER LDB, LDX, N, NRHS

REAL ALPHA, BETA

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

#include <sunperf.h>

void clagtm(char trans, int n, int nrhs, float alpha, complex ∗dl, complex ∗d, complex ∗du, complex ∗cx, int ldx,
 float sbeta, complex ∗cb, int ldb) ;

PURPOSE

CLAGTM 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) REAL
The scalar alpha.  ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0.

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

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

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

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

B (input/output) COMPLEX 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