WZgeev WZgeev2 WZhbev WZhbev2 WZheev WZheev2

WZheev2() Function WZheev2 ( Jobz As  String, Uplo As  String, N As  Long, A As  Variant  ) Eigenvalues and eigenvectors of a Hermitian matrix (complex numbers in pairs of cells) Purpose WZheev2 computes all eigenvalues and, optionally, eigenvectors of a Hermitian matrix A. To represent complex numbers, a real part and an imaginary part are stored in a pair of adjacent cells (a real part in a left cell, and an imaginary part in a right cell). The computed results are stored in the same way. Returns N+1 x 1 (if Jobz = "N"), N+1 x 2N+1 (if Jobz = "V" and Info = 0) Column 1 Column 2 to 2N+1 Rows 1 to N Eigenvalues in ascending order Eigenvectors (if Jobz = "V" and Info = 0) (a real part and an imaginary part are stored in a pair of adjacent columns (a real part is left and an imaginary part is right)) 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] Uplo = "U": Upper triangle of A is stored. = "L": Lower triangle of A is stored. [in] N Order of the matrix A. (N >= 1) [in] A (N x 2N) N x N Hermitian matrix A. Reference LAPACK Example Compute all eigenvalues and eigenvectors of the Hermitian matrix A, where ( 0.20 -0.11+0.93i 0.81-0.37i ) A = ( -0.11-0.93i -0.32 -0.80+0.92i ) ( 0.81+0.37i -0.80-0.92i -0.29 )