slagtm.f File Reference

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Functions/Subroutines
subroutine	slagtm (TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA, B, LDB)
	SLAGTM 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 slagtm	(	character	TRANS,
		integer	N,
		integer	NRHS,
		real	ALPHA,
		real, dimension( * )	DL,
		real, dimension( * )	D,
		real, dimension( * )	DU,
		real, dimension( ldx, * )	X,
		integer	LDX,
		real	BETA,
		real, dimension( ldb, * )	B,
		integer	LDB
	)

SLAGTM 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.

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Purpose:

 SLAGTM 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:

[in]	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
[in]	N	N is INTEGER The order of the matrix A. N >= 0.
[in]	NRHS	NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrices X and B.
[in]	ALPHA	ALPHA is REAL The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0.
[in]	DL	DL is REAL array, dimension (N-1) The (n-1) sub-diagonal elements of T.
[in]	D	D is REAL array, dimension (N) The diagonal elements of T.
[in]	DU	DU is REAL array, dimension (N-1) The (n-1) super-diagonal elements of T.
[in]	X	X is REAL array, dimension (LDX,NRHS) The N by NRHS matrix X.
[in]	LDX	LDX is INTEGER The leading dimension of the array X. LDX >= max(N,1).
[in]	BETA	BETA is REAL The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1.
[in,out]	B	B is REAL 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.
[in]	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 slagtm.f.

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