Intel® oneAPI Math Kernel Library Developer Reference - C
Computes all eigenvalues and, optionally, eigenvectors of a real symmetric tridiagonal matrix.
lapack_int LAPACKE_sstev (int matrix_layout, char jobz, lapack_int n, float* d, float* e, float* z, lapack_int ldz);
lapack_int LAPACKE_dstev (int matrix_layout, char jobz, lapack_int n, double* d, double* e, double* z, lapack_int ldz);
The routine computes all eigenvalues and, optionally, eigenvectors of a real symmetric tridiagonal matrix A.
Specifies whether matrix storage layout is row major (LAPACK_ROW_MAJOR) or column major (LAPACK_COL_MAJOR).
Must be 'N' or 'V'.
If jobz = 'N', then only eigenvalues are computed.
If jobz = 'V', then eigenvalues and eigenvectors are computed.
The order of the matrix A (n≥ 0).
Arrays:
Array d contains the n diagonal elements of the tridiagonal matrix A.
The size of d must be at least max(1, n).
Array e contains the n-1 subdiagonal elements of the tridiagonal matrix A.
The size of e must be at least max(1, n). The n-th element of this array is used as workspace.
The leading dimension of the output array z; ldz≥ 1. If jobz = 'V' then ldz≥ max(1, n).
On exit, if info = 0, contains the eigenvalues of the matrix A in ascending order.
Array, size (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 the eigenvalue returned in d[i - 1].
If job = 'N', then z is not referenced.
On exit, this array is overwritten with intermediate results.
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 elements of e did not converge to zero.