Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

Contents

?hbev

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

Syntax

lapack_int LAPACKE_chbev
(
int
matrix_layout
,
char
jobz
,
char
uplo
,
lapack_int
n
,
lapack_int
kd
,
lapack_complex_float*
ab
,
lapack_int
ldab
,
float*
w
,
lapack_complex_float*
z
,
lapack_int
ldz
);
lapack_int LAPACKE_zhbev
(
int
matrix_layout
,
char
jobz
,
char
uplo
,
lapack_int
n
,
lapack_int
kd
,
lapack_complex_double*
ab
,
lapack_int
ldab
,
double*
w
,
lapack_complex_double*
z
,
lapack_int
ldz
);
Include Files
  • mkl.h
Description
The routine computes all eigenvalues and, optionally, eigenvectors of a complex Hermitian 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 Hermitian 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
Array, size at least max(1,
n
).
If
info
 = 0
, contains the eigenvalues in ascending order.
z
Array
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 hbtrd).
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.
If
info
 =
i
, then the algorithm failed to converge;
i
 indicates the number of elements of an intermediate tridiagonal form which did not converge to zero.

Product and Performance Information

1

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