zhbev zhbevd zhbevx zheev zheevd zheevr zheevx zhpev zhpevd zhpevx

zhbev() void zhbev ( char  jobz, char  uplo, int  n, int  kd, int  ldab, doublecomplex  ab[], double  w[], int  ldz, doublecomplex  z[], doublecomplex  work[], double  rwork[], int *  info  ) (Simple driver) Eigenvalues and eigenvectors of a Hermitian band matrix Purpose This routine computes all the eigenvalues and, optionally, eigenvectors of a Hermitian band matrix A. Eigenvalues and eigenvectors are computed by QL or QR method. 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 >= 0) (If n = 0, returns without computation) [in] kd Number of super-diagonals of the matrix A if uplo = 'U' or number of sub-diagonals if uplo = 'L'. (kd >= 0) [in] ldab Leading dimension of the two dimensional array ab[][]. (ldab >= kd + 1) [in,out] ab[][] Array ab[lab][ldab] (lab >= n) [in] The upper or lower triangle of the Hermitian band matrix A, stored in the first kd+1 columns of the array. The j-th column of A is stored in the j-th row of the array ab as follows. uplo = 'U': ab[j][kd + i - j] = A(i, j) for max(0, j - kd - 1) <= i <= j <= n - 1. uplo = 'L': ab[j][i - j] = A(i, j) for 0 <= j <= i <= min(n - 1, j + kd - 1). [out] ab[][] is overwritten by values generated during the reduction to tridiagonal form. If uplo = 'U', the first superdiagonal and the diagonal of the tridiagonal matrix T are returned in columns kd and kd+1 of ab[][]. If uplo = 'L', the diagonal and first subdiagonal of T are returned in the first two columns of ab[][]. [out] w[] Array w[lw] (lw >= n) If info = 0, the eigenvalues in ascending order. [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 w[i]. jobz = 'N': z[][] is not referenced. [out] work[] Array work[lwork] (lwork >= n) Work array. [out] rwork[] Array rwork[lrwork] (lrwork >= max(1, 3*n-2)) Work array. [out] info = 0: Successful exit = -1: The argument jobz had an illegal value (jobz != 'V' nor 'N') = -2: The argument uplo had an illegal value (uplo != 'U' nor 'L') = -3: The argument n had an illegal value (n < 0) = -4: The argument kd had an illegal value (kd < 0) = -5: The argument ldab had an illegal value (ldab < kd + 1) = -8: The argument ldz had an illegal value (ldz too small) = i > 0: The algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero Reference LAPACK