Developer Reference for Intel® oneAPI Math Kernel Library for C
?hpev
Computes all eigenvalues and, optionally, eigenvectors of a Hermitian matrix in packed storage.
Syntax
lapack_int LAPACKE_chpev ( intmatrix_layout , charjobz , charuplo , lapack_intn , lapack_complex_float*ap , float*w , lapack_complex_float*z , lapack_intldz );
lapack_int LAPACKE_zhpev ( intmatrix_layout , charjobz , charuplo , lapack_intn , lapack_complex_double*ap , double*w , lapack_complex_double*z , lapack_intldz );
Include Files
mkl.h
Description
chpev zhpev hpev
The routine computes all the eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A in packed storage.
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 job = 'N' , then only eigenvalues are computed. If job = 'V' , then eigenvalues and eigenvectors are computed.
uplo
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
The order of the matrix A ( n≥ 0 ).
- ap
-
COMPLEX for chpev DOUBLE COMPLEX for zhpev . Array ap(*) contains the packed upper or lower triangle of Hermitian matrix A, as specified by uplo . The size of ap must be at least max(1, n *( n +1)/2).
- work
-
COMPLEX for chpev DOUBLE COMPLEX for zhpev . (*) is a workspace array, size at least max(1, 2 n -1).
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 chpev DOUBLE PRECISION for zhpev . Workspace array, size at least max(1, 3 n -2).
Output Parameters
- w
-
REAL for chpev DOUBLE PRECISION for zhpev . Array, size at least max(1, n ). If info = 0 , w contains the eigenvalues of the matrix A in ascending order.
- z
-
COMPLEX for chpev DOUBLE COMPLEX for zhpev .
Array z (size at least 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.
- ap
-
On exit, this array is overwritten by the values generated during the reduction to tridiagonal form. The elements of the diagonal and the off-diagonal of the tridiagonal matrix overwrite the corresponding elements of A.
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.