Developer Reference

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

?sbgvd

Computes all eigenvalues and, optionally, eigenvectors of a real generalized symmetric definite eigenproblem with banded matrices. If eigenvectors are desired, it uses a divide and conquer method.

Syntax

call ssbgvd
(
jobz
,
uplo
,
n
,
ka
,
kb
,
ab
,
ldab
,
bb
,
ldbb
,
w
,
z
,
ldz
,
work
,
lwork
,
iwork
,
liwork
,
info
)
call dsbgvd
(
jobz
,
uplo
,
n
,
ka
,
kb
,
ab
,
ldab
,
bb
,
ldbb
,
w
,
z
,
ldz
,
work
,
lwork
,
iwork
,
liwork
,
info
)
call sbgvd
(
ab
,
bb
,
w
[
,
uplo
]
[
,
z
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine computes all the eigenvalues, and optionally, the eigenvectors of a real generalized symmetric-definite banded eigenproblem, of the form
A
*
x
=
λ
*
B
*
x
. Here
A
and
B
are assumed to be symmetric and banded, and
B
is also positive definite.
If eigenvectors are desired, it uses a divide and conquer algorithm.
Input Parameters
jobz
CHARACTER*1
.
Must be
'N'
or
'V'
.
If
jobz
=
'N'
, then compute eigenvalues only.
If
jobz
=
'V'
, then compute eigenvalues and eigenvectors.
uplo
CHARACTER*1
.
Must be
'U'
or
'L'
.
If
uplo
=
'U'
, arrays
ab
and
bb
store the upper triangles of
A
and
B
;
If
uplo
=
'L'
, arrays
ab
and
bb
store the lower triangles of
A
and
B
.
n
INTEGER
.
The order of the matrices
A
and
B
(
n
0
).
ka
INTEGER
.
The number of super- or sub-diagonals in
A
(
ka
0
).
kb
INTEGER
.
The number of super- or sub-diagonals in
B
(
kb
0).
ab
,
bb