rocsolver_cheevx Interface Reference

rocsolver_cheevx Interface Reference#

HIPFORT API Reference: hipfort_rocsolver::rocsolver_cheevx Interface Reference

The HEEVX functions compute a set of the eigenvalues and optionally the corresponding eigenvectors of a Hermitian matrix A. More...

Public Member Functions
integer(kind(rocblas_status_success)) function	rocsolver_cheevx_ (handle, evect, erange, uplo, n, a, lda, vl, vu, il, iu, abstol, nev, w, z, ldz, ifail, myinfo)

Detailed Description

The HEEVX functions compute a set of the eigenvalues and optionally the corresponding eigenvectors of a Hermitian matrix A.

This function computes all the eigenvalues of A, all the eigenvalues in the half-open interval \((vl, vu]\), or the il -th through iu -th eigenvalues, depending on the value of erange. If evect is rocblas_evect_original, the eigenvectors for these eigenvalues will be computed as well.

Parameters

[in]	handle	- rocblas_handle.
[in]	evect	- `rocblas_evect`. Specifies whether the eigenvectors are to be computed. If evect is rocblas_evect_original, then the eigenvectors are computed. rocblas_evect_tridiagonal is not supported.
[in]	erange	- `rocblas_erange`. Specifies the type of range or interval of the eigenvalues to be computed.
[in]	uplo	- rocblas_fill. Specifies whether the upper or lower part of the symmetric matrix A is stored. If uplo indicates lower (or upper), then the upper (or lower) part of A is not used.
[in]	n	- rocblas_int. n >= 0. Number of rows and columns of matrix A.
[in,out]	A	- pointer to type. Array on the GPU of dimension lda*n. On entry, the matrix A. On exit, the contents of A are destroyed.
[in]	lda	- rocblas_int. lda >= n. Specifies the leading dimension of matrix A.
[in]	vl	- real type. vl < vu. The lower bound of the search interval (vl, vu]. Ignored if range indicates to look for all the eigenvalues of A or the eigenvalues within a set of indices.
[in]	vu	- real type. vl < vu. The upper bound of the search interval (vl, vu]. Ignored if range indicates to look for all the eigenvalues of A or the eigenvalues within a set of indices.
[in]	il	- rocblas_int. il = 1 if n = 0, and 1 <= il <= iu otherwise. The index of the smallest eigenvalue to be computed. Ignored if range indicates to look for all the eigenvalues of A or the eigenvalues in a half-open interval.
[in]	iu	- rocblas_int. iu = 0 if n = 0, and 1 <= il <= iu otherwise. The index of the largest eigenvalue to be computed. Ignored if range indicates to look for all the eigenvalues of A or the eigenvalues in a half-open interval.
[in]	abstol	- real type. The absolute tolerance. An eigenvalue is considered to be located if it lies in an interval whose width is <= abstol. If abstol is negative, then machine-epsilon times the 1-norm of the tridiagonal form of A will be used as the tolerance. If abstol=0, then the tolerance will be set to twice the underflow threshold. This is the tolerance that could get the most accurate results.
[out]	nev	- pointer to a rocblas_int on the GPU. The total number of eigenvalues found. If erange is rocblas_erange_all, nev = n. If erange is rocblas_erange_index, nev = iu - il + 1. Otherwise, 0 <= nev <= n.
[out]	W	- pointer to real type. Array on the GPU of dimension n. The first nev elements contain the computed eigenvalues. (The remaining elements can be used as workspace for internal computations.)
[out]	Z	- pointer to type. Array on the GPU of dimension ldz*nev. On exit, if evect is not rocblas_evect_none and info = 0, the first nev columns contain the eigenvectors of A corresponding to the output eigenvalues. Not referenced if evect is rocblas_evect_none. Note: If erange is rocblas_range_value, then the values of nev are not known in advance. The user should ensure that Z is large enough to hold n columns, as all n columns can be used as workspace for internal computations.
[in]	ldz	- rocblas_int. ldz >= n. Specifies the leading dimension of matrix Z.
[out]	ifail	- pointer to rocblas_int. Array on the GPU of dimension n. If info = 0, the first nev elements of ifail are zero. Otherwise, contains the indices of those eigenvectors that failed to converge. Not referenced if evect is rocblas_evect_none.
[out]	myInfo	- pointer to a rocblas_int on the GPU. If info = 0, successful exit. If info = i > 0, the algorithm did not converge. i columns of Z did not converge.

Member Function/Subroutine Documentation