dlagtm (l)  Linux Man Pages
dlagtm: performs a matrixvector 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
Command to display dlagtm
manual in Linux: $ man l dlagtm
NAME
DLAGTM  performs a matrixvector 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
SYNOPSIS
 SUBROUTINE DLAGTM(

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

CHARACTER
TRANS

INTEGER
LDB, LDX, N, NRHS

DOUBLE
PRECISION ALPHA, BETA

DOUBLE
PRECISION B( LDB, * ), D( * ), DL( * ), DU( * ),
X( LDX, * )
PURPOSE
DLAGTM performs a matrixvector product of the form
ARGUMENTS
 TRANS (input) CHARACTER*1

Specifies the operation applied to A.
= aqNaq: No transpose, B := alpha * A * X + beta * B
= aqTaq: Transpose, B := alpha * Aaq* X + beta * B
= aqCaq: Conjugate transpose = Transpose
 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) DOUBLE PRECISION array, dimension (N1)

The (n1) subdiagonal elements of T.
 D (input) DOUBLE PRECISION array, dimension (N)

The diagonal elements of T.
 DU (input) DOUBLE PRECISION array, dimension (N1)

The (n1) superdiagonal elements of T.
 X (input) DOUBLE PRECISION 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) 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 (input) INTEGER

The leading dimension of the array B. LDB >= max(N,1).
Pages related to dlagtm
 dlagtm (3)
 dlagtf (l)  factorizes the matrix (T  lambda*I), where T is an n by n tridiagonal matrix and lambda is a scalar, as T  lambda*I = PLU,
 dlagts (l)  may be used to solve one of the systems of equations (T  lambda*I)*x = y or (T  lambda*I)aq*x = y,
 dlag2 (l)  computes the eigenvalues of a 2 x 2 generalized eigenvalue problem A  w B, with scaling as necessary to avoid over/underflow
 dlag2s (l)  converts a DOUBLE PRECISION matrix, SA, to a SINGLE PRECISION matrix, A
 dlags2 (l)  computes 2by2 orthogonal matrices U, V and Q, such that if ( UPPER ) then Uaq*A*Q = Uaq*( A1 A2 )*Q = ( x 0 ) ( 0 A3 ) ( x x ) and Vaq*B*Q = Vaq*( B1 B2 )*Q = ( x 0 ) ( 0 B3 ) ( x x ) or if ( .NOT.UPPER ) then Uaq*A*Q = Uaq*( A1 0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and Vaq*B*Q = Vaq*( B1 0 )*Q = ( x x ) ( B2 B3 ) ( 0 x ) The rows of the transformed A and B are parallel, where U = ( CSU SNU ), V = ( CSV SNV ), Q = ( CSQ SNQ ) ( SNU CSU ) ( SNV CSV ) ( SNQ CSQ ) Zaq denotes the transpose of Z
 dlagv2 (l)  computes the Generalized Schur factorization of a real 2by2 matrix pencil (A,B) where B is upper triangular
 dla_gbamv (l)  performs one of the matrixvector operations y := alpha*abs(A)*abs(x) + beta*abs(y),