Developer Reference

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

?sbevx

Computes selected eigenvalues and, optionally, eigenvectors of a real symmetric band matrix.

Syntax

call ssbevx
(
jobz
,
range
,
uplo
,
n
,
kd
,
ab
,
ldab
,
q
,
ldq
,
vl
,
vu
,
il
,
iu
,
abstol
,
m
,
w
,
z
,
ldz
,
work
,
iwork
,
ifail
,
info
)
call dsbevx
(
jobz
,
range
,
uplo
,
n
,
kd
,
ab
,
ldab
,
q
,
ldq
,
vl
,
vu
,
il
,
iu
,
abstol
,
m
,
w
,
z
,
ldz
,
work
,
iwork
,
ifail
,
info
)
call sbevx
(
ab
,
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, eigenvectors of a real symmetric band matrix
A
. Eigenvalues and eigenvectors can be selected by specifying either 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 only eigenvalues are computed.
If
jobz
=
'V'
, then eigenvalues and eigenvectors are computed.
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
w
(
i
)
in the half-open interval:
vl
<
w
(
i
)
vu
.
If
range
=
'I'
, the routine computes eigenvalues with indices in range
il
to
iu
.
uplo
CHARACTER*1
.
Must be
'U'
or
'L'
.
If
uplo
=
'U'
,
ab
stores the upper triangular part of
A
.
If
uplo
=
'L'
,
ab
stores the lower triangular part of
A
.
n
INTEGER
.
The order of the matrix
A
(
n