Developer Reference

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

?sygvx

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

Syntax

call ssygvx
(
itype
,
jobz
,
range
,
uplo
,
n
,
a
,
lda
,
b
,
ldb
,
vl
,
vu
,
il
,
iu
,
abstol
,
m
,
w
,
z
,
ldz
,
work
,
lwork
,
iwork
,
ifail
,
info
)
call dsygvx
(
itype
,
jobz
,
range
,
uplo
,
n
,
a
,
lda
,
b
,
ldb
,
vl
,
vu
,
il
,
iu
,
abstol
,
m
,
w
,
z
,
ldz
,
work
,
lwork
,
iwork
,
ifail
,
info
)
call sygvx
(
a
,
b
,
w
[
,
itype
]
[
,
uplo
]
[
,
z
]
[
,
vl
]
[
,
vu
]
[
,
il
]
[
,
iu
]
[
,
m
]
[
,
ifail
]
[
,
abstol
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine computes selected eigenvalues, and optionally, the eigenvectors of a real generalized symmetric-definite eigenproblem, of the form
A
*
x
=
λ
*
B
*
x
,
A
*
B
*
x
=
λ
*
x
, or
B
*
A
*
x
=
λ
*
x
.
Here
A
and
B
are assumed to be symmetric and
B
is also positive definite. Eigenvalues and eigenvectors can be selected by specifying either a range of values or a range of indices for the desired eigenvalues.
Input Parameters
itype
INTEGER
.
Must be 1 or 2 or 3. Specifies the problem type to be solved:
if
itype
= 1
, the problem type is
A*x
=
λ
*B*x
;
if
itype
= 2
, the problem type is
A
*
B
*
x
=
λ
*
x
;
if
itype
= 3
, the problem type is
B*A
*x =
λ
*
x
.
jobz
CHARACTER*1
.
Must be
'N'
or
'V'
.
If
jobz
=
'N'
, then compute eigenvalues only.
If
jobz
=
'V'
, then compute eigenvalues and eigenvectors.
range