Developer Reference

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

?gttrs

Solves a system of linear equations with a tridiagonal coefficient matrix using the LU factorization computed by
?gttrf
.

Syntax

call sgttrs
(
trans
,
n
,
nrhs
,
dl
,
d
,
du
,
du2
,
ipiv
,
b
,
ldb
,
info
)
call dgttrs
(
trans
,
n
,
nrhs
,
dl
,
d
,
du
,
du2
,
ipiv
,
b
,
ldb
,
info
)
call cgttrs
(
trans
,
n
,
nrhs
,
dl
,
d
,
du
,
du2
,
ipiv
,
b
,
ldb
,
info
)
call zgttrs
(
trans
,
n
,
nrhs
,
dl
,
d
,
du
,
du2
,
ipiv
,
b
,
ldb
,
info
)
call gttrs
(
dl
,
d
,
du
,
du2
,
b
,
ipiv
[
,
trans
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine solves for
X
the following systems of linear equations with multiple right hand sides:
A*X
=
B
if
trans
=
'N'
,
A
T
*X
=
B
if
trans
=
'T'
,
A
H
*X
=
B
if
trans
=
'C'
(for complex matrices only).
Before calling this routine, you must call
?gttrf
to compute the
LU
factorization of
A
.
Input Parameters
trans
CHARACTER*1
.
Must be
'N'
or
'T'
or
'C'
.
Indicates the form of the equations:
If
trans
=
'N'
, then
A*X
=
B
is solved for
X
.
If
trans
=
'T'
, then
A
T
*X
=
B
is solved for
X
.
If
trans
=
'C'
, then
A
H
*X
=
B
is solved for
X
.
n
INTEGER
.
The order of
A
;
n
0.
nrhs
INTEGER
.
The number of right-hand sides, that is, the number of columns in
B
;
nrhs
0
.
dl
,
d
,
du
,
du2
,
b