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zhpgv() void zhpgv ( int  itype, char  jobz, char  uplo, int  n, doublecomplex  ap[], doublecomplex  bp[], double  w[], int  ldz, doublecomplex  z[], doublecomplex  work[], double  rwork[], int *  info  ) (Simple driver) Generalized eigenvalue problem of Hermitian matrices in packed form Purpose This routine computes all the eigenvalues, and optionally, the eigenvectors of a complex generalized Hermitian-definite eigenproblem, of the form A*x = lambda*B*x, A*Bx = lambda*x, or B*A*x = lambda*x. Here A and B are assumed to be Hermitian, stored in packed format, and B is also positive definite. Parameters [in] itype Specifies the problem type to be solved: = 1: A*x = lambda*B*x. = 2: A*B*x = lambda*x. = 3: B*A*x = lambda*x. [in] jobz = 'N': Compute eigenvalues only. = 'V': Compute eigenvalues and eigenvectors. [in] uplo = 'U': Upper triangles of A and B are stored. = 'L': Lower triangles of A and B are stored. [in] n Order of the matrices A and B. (n >= 0) (If n = 0, returns without computation) [in,out] ap[] Array ap[lap] (lap >= n(n + 1)/2) [in] The upper or lower triangle of the Hermitian matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array ap as follows. uplo = 'U': ap[i + j*(j + 1)/2] = Aij for 0 <= i <= j <= n - 1. uplo = 'L': ap[(i + j*(2*n - j - 1)/2] = Aij for 0 <= j < = i <= n - 1. [out] The contents of ap[] are destroyed. [in,out] bp[] Array bp[lbp] (lbp >= n(n + 1)/2) [in] The upper or lower triangle of the Hermitian positive definite matrix B, packed columnwise in a linear array. The j-th column of B is stored in the array bp as follows. uplo = 'U': bp[i + j*(j + 1)/2] = Bij for 0 <= i <= j <= n - 1. uplo = 'L': bp[(i + j*(2*n - j - 1)/2] = Bij for 0 <= j < = i <= n - 1. [out] The triangular factor U or L from the Cholesky factorization B = U^H*U or B = L*L^H, in the same storage format as B. [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 if jobz = 'N', ldz >= max(1, n) if jobz = 'V') [out] z[][] Array z[lz][ldz] (lz >= n) jobz = 'V': If info = 0, z[][] contains the matrix Z of eigenvectors. The eigenvectors are normalized as follows:   itype = 1 or 2: Z^H*B*Z = I   itype = 3: Z^H*inv(B)*Z = I jobz = 'N': z[][] is not referenced. [out] work[] Array work[lwork] (lwork >= max(1, 2*n-1)) Complex work array. [out] rwork[] Array rwork[lrwork] (lrwork >= max(1, 3*n-2)) Work array. [out] info = 0: Successful exit = -1: The argument itype had an illegal value (itype < 1 or itype > 3) = -2: The argument jobz had an illegal value (jobz != 'V' nor 'N') = -3: The argument uplo had an illegal value (uplo != 'U' nor 'L') = -4: The argument n had an illegal value (n < 0) = -8: The argument ldz had an illegal value (ldz too small) = i (0 < i <= n): zhpev failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. = i (i > n): The leading minor of order i-n of B is not positive definite. The factorization of B could not be completed and no eigenvalues or eigenvectors were computed. Reference LAPACK