Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?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
*
A
T
*
X
+
beta
*
B
(transpose);
If
trans
=
'C'
, then
B
:=
alpha
*
A
H
*
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
).