stev#

sstev

Functions

void sstev(
    const char*          jobz,
    const INT            n,
          f32*  restrict D,
          f32*  restrict E,
          f32*  restrict Z,
    const INT            ldz,
          f32*  restrict work,
          INT*           info
);

void sstev(const char *jobz, const INT n, f32 *restrict D, f32 *restrict E, f32 *restrict Z, const INT ldz, f32 *restrict work, INT *info)#

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

Parameters

in

jobz

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

in

n

The order of the matrix. n >= 0.

inout

D

Double precision array, dimension (n). On entry, the n diagonal elements of the tridiagonal matrix A. On exit, if info = 0, the eigenvalues in ascending order.

inout

E

Double precision array, dimension (n-1). On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the contents of E are destroyed.

out

Z

Double precision array, dimension (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 D(i). If jobz = ‘N’, then Z is not referenced.

in

ldz

The leading dimension of the array Z. ldz >= 1, and if jobz = ‘V’, ldz >= max(1,n).

out

work

Double precision array, dimension (max(1,2*n-2)). If jobz = ‘N’, work is not referenced.

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 of E did not converge to zero.

dstev

Functions

void dstev(
    const char*          jobz,
    const INT            n,
          f64*  restrict D,
          f64*  restrict E,
          f64*  restrict Z,
    const INT            ldz,
          f64*  restrict work,
          INT*           info
);

void dstev(const char *jobz, const INT n, f64 *restrict D, f64 *restrict E, f64 *restrict Z, const INT ldz, f64 *restrict work, INT *info)#

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

Parameters

in

jobz

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

in

n

The order of the matrix. n >= 0.

inout

D

Double precision array, dimension (n). On entry, the n diagonal elements of the tridiagonal matrix A. On exit, if info = 0, the eigenvalues in ascending order.

inout

E

Double precision array, dimension (n-1). On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the contents of E are destroyed.

out

Z

Double precision array, dimension (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 D(i). If jobz = ‘N’, then Z is not referenced.

in

ldz

The leading dimension of the array Z. ldz >= 1, and if jobz = ‘V’, ldz >= max(1,n).

out

work

Double precision array, dimension (max(1,2*n-2)). If jobz = ‘N’, work is not referenced.

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 of E did not converge to zero.

stev#

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