Zgebak Zgebal Zgehrd Zhsein Zhseqr Ztrevc3 Ztrexc Ztrsen Ztrsna Ztrsyl Zunghr Zunmhr

Ztrexc() Sub Ztrexc ( Compq As  String, N As  Long, T() As  Complex, Q() As  Complex, Ifst As  Long, Ilst As  Long, Info As  Long  ) Reordering of Schur factorization of complex matrix Purpose This routine reorders the Schur factorization of a complex matrix A = Q*T*Q^H, so that the diagonal block of T with row index Ifst is moved to row Ilst. The Schur form T is reordered by a unitary similarity transformation Z^H*T*Z, and optionally the matrix Q of Schur vectors is updated by postmultiplying it with Z. Parameters [in] Compq = "V": Update the matrix Q of Schur vectors. = "N": Do not update Q. [in] N Order of the matrix T. (N >= 0) (If N = 0, returns without computation) [in,out] T() Array T(LT1 - 1, LT2 - 1) (LT1 >= N, LT2 >= N) [in] The upper triangular matrix T. [out] The reordered upper triangular matrix. [in,out] Q() Array Q(LQ1 - 1, LQ2 - 1) (LQ1 >= N, LQ2 >= N) If Compq = "V", [in] The matrix Q of Schur vectors. [out] Q has been postmultiplied by the unitary transformation matrix Z which reorders T. If Compq = "N", Q() is not referenced. [in] Ifst [in] Ilst Specify the reordering of the diagonal elements of T. The element with row index Ifst is moved to row Ilst, by a sequence of transpositions between adjacent elements. (1 <= Ifst <= N, 1 <= Ilst <= N) [out] Info = 0: Successful exit. = -1: The argument Compq had an illegal value. (Copq <> "V" nor "N") = -2: The argument N had an illegal value. (N < 0) = -3: The argument T() is invalid. = -4: The argument Q() is invalid. = -5: The argument Ifst had an illegal value. (Ifst < 1 or Ifst > N) = -6: The argument Ilst had an illegal value. (Ilst < 1 or Ilst > N) Reference LAPACK