LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
|
subroutine sstev | ( | character | JOBZ, |
integer | N, | ||
real, dimension( * ) | D, | ||
real, dimension( * ) | E, | ||
real, dimension( ldz, * ) | Z, | ||
integer | LDZ, | ||
real, dimension( * ) | WORK, | ||
integer | INFO | ||
) |
SSTEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices
Download SSTEV + dependencies [TGZ] [ZIP] [TXT]
SSTEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric tridiagonal matrix A.
[in] | JOBZ | JOBZ is CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors. |
[in] | N | N is INTEGER The order of the matrix. N >= 0. |
[in,out] | D | D is REAL array, dimension (N) On entry, the n diagonal elements of the tridiagonal matrix A. On exit, if INFO = 0, the eigenvalues in ascending order. |
[in,out] | E | E is REAL array, dimension (N-1) On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A, stored in elements 1 to N-1 of E. On exit, the contents of E are destroyed. |
[out] | Z | Z is REAL 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 | LDZ is INTEGER The leading dimension of the array Z. LDZ >= 1, and if JOBZ = 'V', LDZ >= max(1,N). |
[out] | WORK | WORK is REAL array, dimension (max(1,2*N-2)) If JOBZ = 'N', WORK is not referenced. |
[out] | INFO | INFO is INTEGER = 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. |
Definition at line 118 of file sstev.f.