WDgeev WDsbev WDstev WDsyev

WDstev() Function WDstev ( Jobz As  String, N As  Long, D As  Variant, E As  Variant  ) Eigenvalues and eigenvectors of a symmetric tridiagonal matrix Purpose Dstev computes all eigenvalues and, optionally, eigenvectors of a real symmetric tridiagonal matrix A. Returns N+1 x 1 (if Jobz = "N"), N+1 x N+1 (if Jobz = "V" and Info = 0) Column 1 Columns 2 to N+1 Rows 1 to N Eigenvalues in ascending order Eigenvectors (if Jobz = "V" and Info = 0) Row N+1 Return code 0 Return code = 0: Successful exit = i > 0: The i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. Parameters [in] Jobz = "N": Compute eigenvalues only. = "V": Compute eigenvalues and eigenvectors. [in] N Order of the matrix A. (N >= 1) [in] D (N) Diagonal elements of the real symmetric tridiagonal matrix A. [in] E (N-1) Subdiagonal elements of the real symmetric tridiagonal matrix A. Reference LAPACK Example Compute all eigenvalues and eigenvectors of the symmetric tridiagonal matrix A, where ( 2.58 -0.99 0 ) A = ( -0.99 0.69 -0.03 ) ( 0 -0.03 0.18 )