## Developer Reference

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

# ?dtsvb

Computes the solution to the system of linear equations with a diagonally dominant tridiagonal coefficient matrix A and multiple right-hand sides.

## Syntax

Include Files
• mkl.fi
,
lapack.f90
Description
The
?dtsvb
routine solves a system of linear equations
A
*
X
=
B
for
X
, where
A
is an
n
-by-
n
diagonally dominant tridiagonal matrix, the columns of matrix
B
are individual right-hand sides, and the columns of
X
are the corresponding solutions. The routine uses the BABE (Burning At Both Ends) algorithm.
Note that the equation
A
T
*
X
=
B
may be solved by interchanging the order of the arguments
du
and
dl
.
Input Parameters
n
INTEGER
.
The order of
A
, the number of rows in
B
;
n
0.
nrhs
INTEGER
.
The number of right-hand sides, the number of columns in
B
;
nrhs
0.
dl
,
d
,
du
,
b
REAL
for
sdtsvb
DOUBLE PRECISION
for
ddtsvb
COMPLEX
for
cdtsvb
DOUBLE COMPLEX
for
zdtsvb
.
Arrays:
dl
(size
n
- 1),
d
(size
n
),
du
(size
n
- 1),
b
(size
ldb
,*)
.
The array
dl
contains the
(
n
- 1)
subdiagonal elements of
A
.
The array
d
contains the diagonal elements of
A
.
The array
du
contains the
(
n
- 1)
superdiagonal elements of
A
.
The array
b
contains the matrix
B
whose columns are the right-hand sides for the systems of equations.
The second dimension of
b
must be at least
max(1,
nrhs
)
.
ldb
INTEGER
.
b
;
ldb
max(1,
n
)
.
Output Parameters
dl
Overwritten by the
(
n
-1)
elements of the subdiagonal of the lower triangular matrices
L
1
,
L
2
from the factorization of
A
(see dttrfb).
d
Overwritten by the