dsbev dsbevd dsbevx dspev dspevd dspevx dstev dstevd dstevr dstevx dsyev dsyevd dsyevr dsyevx

dstev() void dstev ( char  jobz, int  n, double  d[], double  e[], int  ldz, double  z[], double  work[], int *  info  ) (Simple driver) Eigenvalues and eigenvectors of a symmetric tridiagonal matrix Purpose This routine computes all eigenvalues and, optionally, eigenvectors of a real symmetric tridiagonal matrix A. If eigenvectors are desired, it uses a QL or QR method. Parameters [in] jobz = 'N': Compute eigenvalues only. = 'V': Compute eigenvalues and eigenvectors. [in] n Order of the matrix A. (n >= 0) (If n = 0, returns without computation) [in,out] d[] Array d[ld] (ld >= n) [in] n diagonal elements of the symmetric tridiagonal matrix A. [out] If info = 0, the eigenvalues in ascending order. [in,out] e[] Array e[le] (le >= n - 1) [in] n-1 subdiagonal elements of the symmetric tridiagonal matrix A stored in elements 0 to n-2 of e[]. [out] The contents of e[] are destroyed. [in] ldz Leading dimension of the two dimensional array z[][]. (ldz >= 1 (jobz = 'N'), ldz >= max(1, n) (jobz = 'V')) [out] z[][] Array z[lz][ldz] (lz >= n) jobz = 'V': If info = 0, z[][] contains the orthonormal eigenvectors of the matrix A, with the i-th row of z[][] holding the eigenvector associated with d[i]. jobz = 'N': z[][] is not referenced. [out] work[] Array work[lwork] (lwork >= max(1, 2*n-2)) Work array. If jobz = 'N', work[] is not referenced. [out] info = 0: Successful exit = -1: The argument jobz had an illegal value (jobz != 'V' nor 'N') = -2: The argument n had an illegal value (n < 0) = -5: The argument ldz had an illegal value (ldz too small) = i > 0: The algorithm failed to converge; i off-diagonal elements of e[] did not converge to zero Reference LAPACK