Computes all eigenvalues and, optionally, eigenvectors of a real symmetric band matrix.
lapack_int LAPACKE_ssbev (int matrix_layout, char jobz, char uplo, lapack_int n, lapack_int kd, float* ab, lapack_int ldab, float* w, float* z, lapack_int ldz);
lapack_int LAPACKE_dsbev (int matrix_layout, char jobz, char uplo, lapack_int n, lapack_int kd, double* ab, lapack_int ldab, double* w, double* z, lapack_int ldz);
The routine computes all eigenvalues and, optionally, eigenvectors of a real symmetric band 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.
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.
The order of the matrix A (n≥ 0).
The number of super- or sub-diagonals in A
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 symmetric matrix A (as specified by uplo) in band storage format.
The leading dimension of ab; must be at least kd +1 for column major layout and n for row major layout.
The leading dimension of the output array z.
if jobz = 'N', then ldz≥ 1;
if jobz = 'V', then ldz≥ max(1, n) .
- w, z
w, size at least max(1, n).
If info = 0, contains the eigenvalues of the matrix A in ascending order.
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.
On exit, this array is overwritten by the values generated during the reduction to tridiagonal form (see the description of ?sbtrd).
This function returns a value info.
If info=0, the execution is successful.
If info = -i, the i-th parameter had an illegal value.