Ztbcon Ztbtrs Ztpcon Ztptri Ztptrs Ztrcon Ztrtri Ztrtrs

Ztptri() Sub Ztptri ( Uplo As  String, Diag As  String, N As  Long, Ap() As  Complex, Info As  Long  ) Inverse of a complex triangular matrix in packed form Purpose This routine computes the inverse of a complex upper or lower triangular matrix A stored in packed form. Parameters [in] Uplo = "U": A is upper triangular. = "L": A is lower triangular. [in] Diag = "N": A is non-unit triangular. = "U": A is unit triangular. (Diagonal elements of Ap() are not referenced and are assumed to be 1) [in] N Order of the matrix A. (N >= 0) (If N = 0, returns without computation) [in] Ap() Array Ap(LAp - 1) (LAp >= N(N + 1)/2) [in] N x N triangular matrix A in packed symmetric matrix form. Upper or lower part is to be stored in accordance with Uplo. [out] The (triangular) inverse of the original matrix, in the same packed form. [out] Info = 0: Successful exit. = -1: The argument Uplo had an illegal value. (Uplo <> "U" nor "L") = -2: The argument Diag had an illegal value. (Diag <> "N" nor "U") = -3: The argument N had an illegal value. (N < 0) = -4: The argument Ap() is invalid. = i > 0: The i-th diagonal element of A is exactly zero. The triangular matrix is singular and its inverse can not be computed. Reference LAPACK Example Program Compute the inverse matrix of A, where ( 0.20-0.11i 0 0 ) A = ( -0.93-0.32i 0.81+0.37i 0 ) ( -0.80-0.92i -0.29+0.86i 0.64+0.51i ) Sub Ex_Ztptri() Const N = 3 Dim Ap(N * (N + 1) / 2) As Complex, Info As Long Ap(0) = Cmplx(0.2, -0.11) Ap(1) = Cmplx(-0.93, -0.32): Ap(3) = Cmplx(0.81, 0.37) Ap(2) = Cmplx(-0.8, -0.92): Ap(4) = Cmplx(-0.29, 0.86): Ap(5) = Cmplx(0.64, 0.51) Call Ztptri("L", "N", N, Ap(), Info) Debug.Print "Inv(A) =" Debug.Print Creal(Ap(0)), Cimag(Ap(0)) Debug.Print Creal(Ap(1)), Cimag(Ap(1)), Creal(Ap(3)), Cimag(Ap(3)) Debug.Print Creal(Ap(2)), Cimag(Ap(2)), Creal(Ap(4)), Cimag(Ap(4)) Debug.Print Creal(Ap(5)), Cimag(Ap(5)) Debug.Print "Info =", Info End Sub Example Results Inv(A) = 3.83877159309021 2.11132437619962 4.44578642778825 1.9098735819418 1.02143757881463 -0.466582597730139 5.36621770339369 -1.22742914259824 -0.87238813712865 -0.888792689354233 0.955651784381066 -0.761535015678662 Info = 0