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dlagtm.f(3) LAPACK dlagtm.f(3)

NAME

dlagtm.f -

SYNOPSIS

Functions/Subroutines


subroutine dlagtm (TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA, B, LDB)
DLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1.

Function/Subroutine Documentation

subroutine dlagtm (characterTRANS, integerN, integerNRHS, double precisionALPHA, double precision, dimension( * )DL, double precision, dimension( * )D, double precision, dimension( * )DU, double precision, dimension( ldx, * )X, integerLDX, double precisionBETA, double precision, dimension( ldb, * )B, integerLDB)

DLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1.

Purpose:


DLAGTM performs 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
0., 1., or -1.

Parameters:

TRANS


TRANS is CHARACTER*1
Specifies the operation applied to A.
= 'N': No transpose, B := alpha * A * X + beta * B
= 'T': Transpose, B := alpha * A'* X + beta * B
= 'C': Conjugate transpose = Transpose

N


N is INTEGER
The order of the matrix A. N >= 0.

NRHS


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

ALPHA


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

DL


DL is DOUBLE PRECISION array, dimension (N-1)
The (n-1) sub-diagonal elements of T.

D


D is DOUBLE PRECISION array, dimension (N)
The diagonal elements of T.

DU


DU is DOUBLE PRECISION array, dimension (N-1)
The (n-1) super-diagonal elements of T.

X


X is DOUBLE PRECISION array, dimension (LDX,NRHS)
The N by NRHS matrix X.

LDX


LDX is INTEGER
The leading dimension of the array X. LDX >= max(N,1).

BETA


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

B


B is DOUBLE PRECISION 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


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

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 145 of file dlagtm.f.

Author

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Tue Sep 25 2012 Version 3.4.2