Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

?sbev

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

Syntax

lapack_int
LAPACKE_ssbev
(
int
matrix_layout
,
char
jobz
,
char
uplo
,
lapack_int
n
,
lapack_int
kd
,
float
*
ab
,
lapack_int
ldab
,
float
*
w
,
float
*
z
,
lapack_int
ldz
);
lapack_int
LAPACKE_dsbev
(
int
matrix_layout
,
char
jobz
,
char
uplo
,
lapack_int
n
,
lapack_int
kd
,
double
*
ab
,
lapack_int
ldab
,
double
*
w
,
double
*
z
,
lapack_int
ldz
);
Include Files
  • mkl.h
Description
The routine computes all eigenvalues and, optionally, eigenvectors of a real symmetric band matrix
A
.
Input Parameters
matrix_layout
Specifies whether matrix storage layout is row major (
LAPACK_ROW_MAJOR
) or column major (
LAPACK_COL_MAJOR
).
jobz
Must be
'N'
or
'V'
.
If
jobz
=
'N'
, then only eigenvalues are computed.
If
jobz
=
'V'
, then eigenvalues and eigenvectors are computed.
uplo
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
The order of the matrix
A
(
n
0
).
kd
The number of super- or sub-diagonals in
A
(
kd
0
).
ab
ab
(size at least max(1,
ldab
*
n
) for column major layout and at least max(1,
ldab
*(
kd
+ 1)) for row major layout)
is an array containing either upper or lower triangular part of the symmetric matrix
A
(as specified by
uplo
) in band storage format.
ldab
The leading dimension of
ab
; must be at least
kd
+1
for column major layout and
n
for row major layout
.
ldz
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
Arrays:
w
, size at least max(1,
n
).
If
info
= 0
, contains the eigenvalues of the matrix
A
in ascending order.
z
(size max(1,
ldz
*
n
)
.
If
jobz
=
'V'
, then if
info
= 0
,
z
contains the orthonormal eigenvectors of the matrix
A
, with the
i
-th column of
z
holding the eigenvector associated with
w
[
i
- 1]
.
If
jobz
=
'N'
, then
z
is not referenced.
ab
On exit, this array is overwritten by the values generated during the reduction to tridiagonal form (see the description of ?sbtrd).
Return Values
This function returns a value
info
.
If
info
=0
, the execution is successful.
If
info
=
-i
, the
i
-th parameter had an illegal value.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.