Zpocon Zpotrf Zpotri Zpotrs Zppcon Zpptrf Zpptri Zpptrs

Zpptri() Sub Zpptri ( Uplo As  String, N As  Long, Ap() As  Complex, Info As  Long  ) Inverse of a Hermitian positive definite matrix in packed form Purpose This routine computes the inverse of a Hermitian positive definite matrix A in packed form using the Cholesky factorization A = U^H*U or A = L*L^H computed by zpptrf. Parameters [in] Uplo = "U": Upper triangular factor U is stored in Ap(). = "L": Lower triangular factor L is stored in Ap(). [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] The triangular factor U or L in packed form from the Cholesky factorization A = U^H*U or A = L*L^H, as computed by Zpptrf. [out] If Info = 0, the upper or lower triangle of the (Hermitian) inverse of A, overwriting the input factor U or L. [out] Info = 0: Successful exit. = -1: The argument Uplo had an illegal value. (Uplo <> "U" nor "L") = -2: The argument N had an illegal value. (N < 0) = -3: The argument Ap() is invalid. = i > 0: The i-th diagonal element of the factor U or L is zero, and the inverse could not be computed. Reference LAPACK Example Program Compute the inverse matrix of A, where ( 2.20 -0.11+0.93i 0.81-0.37i ) A = ( -0.11-0.93i 2.32 -0.80+0.92i ) ( 0.81+0.37i -0.80-0.92i 2.29 ) Sub Ex_Zpptri() Const N = 3 Dim Ap(N * (N + 1) / 2) As Complex, Info As Long Ap(0) = Cmplx(2.2, 0) Ap(1) = Cmplx(-0.11, -0.93): Ap(3) = Cmplx(2.32, 0) Ap(2) = Cmplx(0.81, 0.37): Ap(4) = Cmplx(-0.8, -0.92): Ap(5) = Cmplx(2.29, 0) Call Zpptrf("L", N, Ap(), Info) If Info = 0 Then Call Zpptri("L", 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) = 0.96823675342099 0 -0.186364825657161 0.652567887151733 1.07415978942926 0 -0.669749382959094 -3.34014351483294E-03 0.335735031475792 0.692472480506973 1.06960504827267 0 Info = 0