Provided by: liblapack-doc_3.12.1-4_all 
NAME
lagtm - lagtm: tridiagonal matrix-matrix multiply
SYNOPSIS
Functions
subroutine clagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb)
CLAGTM 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.
subroutine dlagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb)
DLAGTM 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.
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.
subroutine zlagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb)
ZLAGTM 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.
Detailed Description
Function Documentation
subroutine clagtm (character trans, integer n, integer nrhs, real alpha, complex, dimension( * ) dl, complex,
dimension( * ) d, complex, dimension( * ) du, complex, dimension( ldx, * ) x, integer ldx, real beta,
complex, dimension( ldb, * ) b, integer ldb)
CLAGTM 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.
Purpose:
CLAGTM performs a matrix-matrix 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
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**T * X + beta * B
= 'C': Conjugate transpose, B := alpha * A**H * X + beta * B
N
N is INTEGER
The order of the matrix A. N >= 0.
NRHS
NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices X and B.
ALPHA
ALPHA is REAL
The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise,
it is assumed to be 0.
DL
DL is COMPLEX array, dimension (N-1)
The (n-1) sub-diagonal elements of T.
D
D is COMPLEX array, dimension (N)
The diagonal elements of T.
DU
DU is COMPLEX array, dimension (N-1)
The (n-1) super-diagonal elements of T.
X
X is COMPLEX array, dimension (LDX,NRHS)
The N by NRHS matrix X.
LDX
LDX is INTEGER
The leading dimension of the array X. LDX >= max(N,1).
BETA
BETA is REAL
The scalar beta. BETA must be 0., 1., or -1.; otherwise,
it is assumed to be 1.
B
B is COMPLEX 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
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.
subroutine dlagtm (character trans, integer n, integer nrhs, double precision alpha, double precision,
dimension( * ) dl, double precision, dimension( * ) d, double precision, dimension( * ) du, double
precision, dimension( ldx, * ) x, integer ldx, double precision beta, double precision, dimension( ldb, *
) b, integer ldb)
DLAGTM 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.
Purpose:
DLAGTM performs a matrix-matrix 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
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
N
N is INTEGER
The order of the matrix A. N >= 0.
NRHS
NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices X and B.
ALPHA
ALPHA is DOUBLE PRECISION
The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise,
it is assumed to be 0.
DL
DL is DOUBLE PRECISION array, dimension (N-1)
The (n-1) sub-diagonal elements of T.
D
D is DOUBLE PRECISION array, dimension (N)
The diagonal elements of T.
DU
DU is DOUBLE PRECISION array, dimension (N-1)
The (n-1) super-diagonal elements of T.
X
X is DOUBLE PRECISION array, dimension (LDX,NRHS)
The N by NRHS matrix X.
LDX
LDX is INTEGER
The leading dimension of the array X. LDX >= max(N,1).
BETA
BETA is DOUBLE PRECISION
The scalar beta. BETA must be 0., 1., or -1.; otherwise,
it is assumed to be 1.
B
B is 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
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.
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.
Purpose:
SLAGTM performs a matrix-matrix 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
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
N
N is INTEGER
The order of the matrix A. N >= 0.
NRHS
NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices X and B.
ALPHA
ALPHA is REAL
The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise,
it is assumed to be 0.
DL
DL is REAL array, dimension (N-1)
The (n-1) sub-diagonal elements of T.
D
D is REAL array, dimension (N)
The diagonal elements of T.
DU
DU is REAL array, dimension (N-1)
The (n-1) super-diagonal elements of T.
X
X is REAL array, dimension (LDX,NRHS)
The N by NRHS matrix X.
LDX
LDX is INTEGER
The leading dimension of the array X. LDX >= max(N,1).
BETA
BETA is REAL
The scalar beta. BETA must be 0., 1., or -1.; otherwise,
it is assumed to be 1.
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.
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.
subroutine zlagtm (character trans, integer n, integer nrhs, double precision alpha, complex*16, dimension( *
) dl, complex*16, dimension( * ) d, complex*16, dimension( * ) du, complex*16, dimension( ldx, * ) x,
integer ldx, double precision beta, complex*16, dimension( ldb, * ) b, integer ldb)
ZLAGTM 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.
Purpose:
ZLAGTM performs a matrix-matrix 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
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**T * X + beta * B
= 'C': Conjugate transpose, B := alpha * A**H * X + beta * B
N
N is INTEGER
The order of the matrix A. N >= 0.
NRHS
NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices X and B.
ALPHA
ALPHA is DOUBLE PRECISION
The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise,
it is assumed to be 0.
DL
DL is COMPLEX*16 array, dimension (N-1)
The (n-1) sub-diagonal elements of T.
D
D is COMPLEX*16 array, dimension (N)
The diagonal elements of T.
DU
DU is COMPLEX*16 array, dimension (N-1)
The (n-1) super-diagonal elements of T.
X
X is COMPLEX*16 array, dimension (LDX,NRHS)
The N by NRHS matrix X.
LDX
LDX is INTEGER
The leading dimension of the array X. LDX >= max(N,1).
BETA
BETA is DOUBLE PRECISION
The scalar beta. BETA must be 0., 1., or -1.; otherwise,
it is assumed to be 1.
B
B is COMPLEX*16 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
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.
Author
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Version 3.12.0 Sun Jul 20 2025 01:40:05 lagtm(3)