slagtm (l) - Linux Manuals
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
Command to display slagtm
manual in Linux: $ man l slagtm
NAME
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
SYNOPSIS
- SUBROUTINE SLAGTM(
-
TRANS, N, NRHS, ALPHA, DL, D, DU, X, LDX, BETA,
B, LDB )
-
CHARACTER
TRANS
-
INTEGER
LDB, LDX, N, NRHS
-
REAL
ALPHA, BETA
-
REAL
B( LDB, * ), D( * ), DL( * ), DU( * ),
X( LDX, * )
PURPOSE
SLAGTM performs a matrix-vector 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) REAL
-
The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise,
it is assumed to be 0.
- DL (input) REAL array, dimension (N-1)
-
The (n-1) sub-diagonal elements of T.
- D (input) REAL array, dimension (N)
-
The diagonal elements of T.
- DU (input) REAL array, dimension (N-1)
-
The (n-1) super-diagonal elements of T.
- X (input) REAL 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) 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.
- LDB (input) INTEGER
-
The leading dimension of the array B. LDB >= max(N,1).
Pages related to slagtm
- slagtm (3)
- slagtf (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,
- slagts (l) - may be used to solve one of the systems of equations (T - lambda*I)*x = y or (T - lambda*I)aq*x = y,
- slag2 (l) - computes the eigenvalues of a 2 x 2 generalized eigenvalue problem A - w B, with scaling as necessary to avoid over-/underflow
- slag2d (l) - converts a SINGLE PRECISION matrix, SA, to a DOUBLE PRECISION matrix, A
- slags2 (l) - computes 2-by-2 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
- slagv2 (l) - computes the Generalized Schur factorization of a real 2-by-2 matrix pencil (A,B) where B is upper triangular
- sla_gbamv (l) - performs one of the matrix-vector operations y := alpha*abs(A)*abs(x) + beta*abs(y),