Developer Reference

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

?sbgvx

Computes selected eigenvalues and, optionally, eigenvectors of a real generalized symmetric definite eigenproblem with banded matrices.

Syntax

call ssbgvx
(
jobz
,
range
,
uplo
,
n
,
ka
,
kb
,
ab
,
ldab
,
bb
,
ldbb
,
q
,
ldq
,
vl
,
vu
,
il
,
iu
,
abstol
,
m
,
w
,
z
,
ldz
,
work
,
iwork
,
ifail
,
info
)
call dsbgvx
(
jobz
,
range
,
uplo
,
n
,
ka
,
kb
,
ab
,
ldab
,
bb
,
ldbb
,
q
,
ldq
,
vl
,
vu
,
il
,
iu
,
abstol
,
m
,
w
,
z
,
ldz
,
work
,
iwork
,
ifail
,
info
)
call sbgvx
(
ab
,
bb
,
w
[
,
uplo
]
[
,
z
]
[
,
vl
]
[
,
vu
]
[
,
il
]
[
,
iu
]
[
,
m
]
[
,
ifail
]
[
,
q
]
[
,
abstol
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine computes selected 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. Eigenvalues and eigenvectors can be selected by specifying either all eigenvalues, a range of values or a range of indices for the desired eigenvalues.
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.
range
CHARACTER*1
.
Must be
'A'
or
'V'
or
'I'
.
If
range
=
'A'
, the routine computes all eigenvalues.
If
range
=
'V'
, the routine computes eigenvalues
lambda
(
i
)
in the half-open interval:
vl
<
lambda
(
i
)
vu
.
If
range
=
'I'
, the routine computes eigenvalues in range
il
to
iu
.
uplo