Developer Reference for Intel® oneAPI Math Kernel Library for C
?hbev
Computes all eigenvalues and, optionally, eigenvectors of a Hermitian band matrix.
Syntax
lapack_int LAPACKE_chbev ( intmatrix_layout , charjobz , charuplo , lapack_intn , lapack_intkd , lapack_complex_float*ab , lapack_intldab , float*w , lapack_complex_float*z , lapack_intldz );
lapack_int LAPACKE_zhbev ( intmatrix_layout , charjobz , charuplo , lapack_intn , lapack_intkd , lapack_complex_double*ab , lapack_intldab , double*w , lapack_complex_double*z , lapack_intldz );
Include Files
mkl.h
Description
chbev zhbev hbev
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 , work
-
COMPLEX for chbev DOUBLE COMPLEX for zhbev . Arrays:
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.
The second dimension of ab must be at least max(1, n ). work (*) is a workspace array. The dimension of work must be at least max(1, n ).
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 ) .
- rwork
-
REAL for chbev DOUBLE PRECISION for zhbev Workspace array, size at least max(1, 3 n -2).
Output Parameters
- w
-
REAL for chbev DOUBLE PRECISION for zhbev Array, size at least max(1, n ). If info = 0 , contains the eigenvalues in ascending order.
- z
-
COMPLEX for chbev DOUBLE COMPLEX for zhbev .
Array z (size max(1, ldz * n ) .
The second dimension of z must be at least max(1, 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)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.
LAPACK 95 Interface Notes
There exist FORTRAN 77 and FORTRAN 95 interfaces for this routine. See the Intel® oneMKL Fortran Developer Reference for details.