Contents

# ?dttrsv

Solves a general tridiagonal system of linear equations using the LU factorization computed by
?dttrf
.

## Syntax

Include Files
• mkl_scalapack.h
Description
The
?dttrsv
function
solves one of the following systems of linear equations:
L*X
=
B
,
L
T
*X
=
B
, or
L
H
*X
=
B
,
U*X
=
B
,
U
T
*X
=
B
, or
U
H
*X
=
B
with factors of the tridiagonal matrix
A
from the
LU
factorization computed by
?dttrf
.
Input Parameters
uplo
Specifies whether to solve with
L
or
U
.
trans
Must be
'N'
or
'T'
or
'C'
.
Indicates the form of the equations:
If
trans
=
'N'
, then
A
*
X
=
B
is solved for
X
(no transpose).
If
trans
=
'T'
, then
A
T
*
X
=
B
is solved for
X
(transpose).
If
trans
=
'C'
, then
A
H
*
X
=
B
is solved for
X
(conjugate transpose).
n
The order of the matrix
A
(
n
0)
.
nrhs
The number of right-hand sides, that is, the number of columns in the matrix
B
(
nrhs
0)
.
dl
,
d
,
du
,
b
The array
dl
of size (
n
- 1) contains the (
n
- 1) multipliers that define the matrix
L
from the
LU
factorization of
A
.
The array
d
of size
n
contains
n
diagonal elements of the upper triangular matrix
U
from the
LU
factorization of
A
.
The array
du
of size (
n
- 1) contains the (
n
- 1) elements of the first super-diagonal of
U
.
On entry, the array
b
of size
ldb
*
nrhs
contains the right-hand side of matrix
B
.
ldb
The leading dimension of the array
b
;
ldb
max(1,
n
)
.
Output Parameters
b
Overwritten by the solution matrix
X
.
info
If
info
=0
, the execution is successful.
If
info
=
-i
, the
i
-th parameter had an illegal value.

#### Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.