syev

ssyev

Functions

void ssyev(
    const char*          jobz,
    const char*          uplo,
    const INT            n,
          f32*  restrict A,
    const INT            lda,
          f32*  restrict W,
          f32*  restrict work,
    const INT            lwork,
          INT*           info
);

void ssyev(const char *jobz, const char *uplo, const INT n, f32 *restrict A, const INT lda, f32 *restrict W, f32 *restrict work, const INT lwork, INT *info)

SSYEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A.

Parameters

in

jobz

= ‘N’: Compute eigenvalues only; = ‘V’: Compute eigenvalues and eigenvectors.

in

uplo

= ‘U’: Upper triangle of A is stored; = ‘L’: Lower triangle of A is stored.

in

n

The order of the matrix A. n >= 0.

inout

A

On entry, the symmetric matrix A. If UPLO = ‘U’, the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A. If UPLO = ‘L’, the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A. On exit, if JOBZ = ‘V’, then A contains the orthonormal eigenvectors of the matrix A. If JOBZ = ‘N’, then on exit the lower/upper triangle of A, including the diagonal, is destroyed.

in

lda

The leading dimension of A. lda >= max(1, n).

out

W

Array of dimension (n). The eigenvalues in ascending order.

out

work

Workspace array, dimension (max(1, lwork)). On exit, if info = 0, work[0] returns the optimal lwork.

in

lwork

The dimension of work. lwork >= max(1, 3*n-1). For optimal efficiency, lwork >= (NB+2)*N where NB is the blocksize for SSYTRD. If lwork = -1, workspace query only.

out

info

• = 0: successful exit

• < 0: if info = -i, the i-th argument had an illegal value

• > 0: if info = i, the algorithm failed to converge; i off-diagonal elements did not converge to zero.

dsyev

Functions

void dsyev(
    const char*          jobz,
    const char*          uplo,
    const INT            n,
          f64*  restrict A,
    const INT            lda,
          f64*  restrict W,
          f64*  restrict work,
    const INT            lwork,
          INT*           info
);

void dsyev(const char *jobz, const char *uplo, const INT n, f64 *restrict A, const INT lda, f64 *restrict W, f64 *restrict work, const INT lwork, INT *info)

DSYEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A.

Parameters

in

jobz

= ‘N’: Compute eigenvalues only; = ‘V’: Compute eigenvalues and eigenvectors.

in

uplo

= ‘U’: Upper triangle of A is stored; = ‘L’: Lower triangle of A is stored.

in

n

The order of the matrix A. n >= 0.

inout

A

On entry, the symmetric matrix A. If UPLO = ‘U’, the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A. If UPLO = ‘L’, the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A. On exit, if JOBZ = ‘V’, then A contains the orthonormal eigenvectors of the matrix A. If JOBZ = ‘N’, then on exit the lower/upper triangle of A, including the diagonal, is destroyed.

in

lda

The leading dimension of A. lda >= max(1, n).

out

W

Array of dimension (n). The eigenvalues in ascending order.

out

work

Workspace array, dimension (max(1, lwork)). On exit, if info = 0, work[0] returns the optimal lwork.

in

lwork

The dimension of work. lwork >= max(1, 3*n-1). For optimal efficiency, lwork >= (NB+2)*N where NB is the blocksize for DSYTRD. If lwork = -1, workspace query only.

out

info

• = 0: successful exit

• < 0: if info = -i, the i-th argument had an illegal value

• > 0: if info = i, the algorithm failed to converge; i off-diagonal elements did not converge to zero.