Developer Reference

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

?spev

Computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix in packed storage.

Syntax

call sspev
(
jobz
,
uplo
,
n
,
ap
,
w
,
z
,
ldz
,
work
,
info
)
call dspev
(
jobz
,
uplo
,
n
,
ap
,
w
,
z
,
ldz
,
work
,
info
)
call spev
(
ap
,
w
[
,
uplo
]
[
,
z
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix
A
in packed storage.
Input Parameters
jobz
CHARACTER*1
.
Must be
'N'
or
'V'
.
If
job
=
'N'
, then only eigenvalues are computed.
If
job
=
'V'
, then eigenvalues and eigenvectors are computed.
uplo
CHARACTER*1
.
Must be
'U'
or
'L'
.
If
uplo
=
'U'
,
ap
stores the packed upper triangular part of
A
.
If
uplo
=
'L'
,
ap
stores the packed lower triangular part of
A
.
n
INTEGER
.
The order of the matrix
A
(
n
0
).
ap
,
work
REAL
for
sspev
DOUBLE PRECISION
for
dspev
Arrays:
Array
ap
(*)
contains the packed upper or lower triangle of symmetric matrix
A
, as specified by
uplo
.
The size of
ap
must be at least max(1,
n
*(
n
+1)/2).
work
(*) is a workspace array, size at least max(1, 3
n
).
ldz
INTEGER
.
The leading dimension of the output array
z
. Constraints:
if
jobz
=
'N'
, then
ldz
1
;
if
jobz
=
'V'
, then
ldz
max(1,
n
)
.
Output Parameters
w
,
z
REAL
for
sspev
DOUBLE PRECISION
for
dspev
Arrays:
w
(*)
, size at least max(1,
n
).
If
info
= 0
,
w
contains the eigenvalues of the matrix
A
in ascending order.