Visible to Intel only — GUID: GUID-ADCE7134-813C-4525-8AE2-4C5DD000A577
Visible to Intel only — GUID: GUID-ADCE7134-813C-4525-8AE2-4C5DD000A577
?lagtm
Performs a matrix-matrix product of the form C = alpha*A*B+beta*C, where A is a tridiagonal matrix, B and C are rectangular matrices, and alpha and beta are scalars, which may be 0, 1, or -1.
Syntax
call slagtm( trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb )
call dlagtm( trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb )
call clagtm( trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb )
call zlagtm( trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb )
Include Files
- mkl.fi
Description
The routine 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.
Input Parameters
- trans
-
CHARACTER*1. Must be 'N' or 'T' or 'C'.
Indicates the form of the equations:
If trans = 'N', then B := alpha*A*X + beta*B (no transpose);
If trans = 'T', then B := alpha*AT*X + beta*B (transpose);
If trans = 'C', then B := alpha*AH*X + beta*B (conjugate transpose)
- n
-
INTEGER. The order of the matrix A (n≥ 0).
- nrhs
-
INTEGER. The number of right-hand sides, i.e., the number of columns in X and B (nrhs≥ 0).
- alpha, beta
-
REAL for slagtm/clagtm
DOUBLE PRECISION for dlagtm/zlagtm
Specify the scalars alpha and beta respectively. alpha must be 0., 1., or -1.; otherwise, it is assumed to be 0. beta must be 0., 1., or -1.; otherwise, it is assumed to be 1.
- dl, d, du
-
REAL for slagtm
DOUBLE PRECISION for dlagtm
COMPLEX for clagtm
DOUBLE COMPLEX for zlagtm.
Arrays: dl(n - 1), d(n), du(n - 1).
The array dl contains the (n - 1) sub-diagonal elements of T.
The array d contains the n diagonal elements of T.
The array du contains the (n - 1) super-diagonal elements of T.
- x, b
-
REAL for slagtm
DOUBLE PRECISION for dlagtm
COMPLEX for clagtm
DOUBLE COMPLEX for zlagtm.
Arrays:
x(ldx,*) contains the n-by-nrhs matrix X. The second dimension of x must be at least max(1, nrhs).
b(ldb,*) contains the n-by-nrhs matrix B. The second dimension of b must be at least max(1, nrhs).
- ldx
-
INTEGER. The leading dimension of the array x; ldx≥ max(1, n).
- ldb
-
INTEGER. The leading dimension of the array b; ldb≥ max(1, n).
Output Parameters
- b
-
Overwritten by the matrix expression B := alpha*A*X + beta*B