DLAGTM
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.
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.
Arguments
| TRANS |
(input) 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 |
(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 (N-1)
The (n-1) sub-diagonal elements of T.
|
| D |
(input) DOUBLE PRECISION array, dimension (N)
The diagonal elements of T.
|
| DU |
(input) DOUBLE PRECISION array, dimension (N-1)
The (n-1) super-diagonal 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).
|