d12r2.txt

Visual Basic 常用数学算法集书中收录了所有代码

Private Sub Command1_Click()
    'PROGRAM D12R2
    'Driver for routine TWOFFT
    N = 32
    N2 = 2 * N
    PER = 8#
    PI = 3.1415926
    Dim DATA1(32), DATA2(32), FFT1(64), FFT2(64)
    For I = 1 To N
        X = 2# * PI * I / PER
        DATA1(I) = CInt(Cos(X))
        DATA2(I) = CInt(Sin(X))
    Next I
    Call TWOFFT(DATA1(), DATA2(), FFT1(), FFT2(), N)
    Print Tab(5); "Fourier transform of first function:"
    Call PRNTFT(FFT1(), N2)
    Print Tab(5); "Fourier transform of second function:"
    Call PRNTFT(FFT2(), N2)
    'Invert transform
    ISIGN = -1
    Call FOUR1(FFT1(), N, ISIGN)
    Print Tab(5); "Inverted transform = first function:"
    Call PRNTFT(FFT1(), N2)
    Call FOUR1(FFT2(), N, ISIGN)
    Print Tab(5); "Inverted transform = second function:"
    Call PRNTFT(FFT2(), N2)
End Sub
Sub PRNTFT(DATA(), N2)
    Print Tab(5); "n  Real(n)  Imag.(n)  Real(N-n)  Imag.(N-n)"
    Print Tab(5); Format$(0, "0");
    Print Tab(12); Format$(DATA(1), "##.#####0");
    Print Tab(25); Format$(DATA(2), "##.#####0");
    Print Tab(38); Format$(DATA(1), "##.#####0");
    Print Tab(51); Format$(DATA(2), "##.#####0")
    For I = 3 To (N2 / 2) + 1 Step 2
        M = (I - 1) / 2
        NN2 = N2 + 2 - I
        Print Tab(5); Format$(M, "0");
        Print Tab(12); Format$(DATA(I), "##.#####0");
        Print Tab(25); Format$(DATA(I + 1), "##.#####0");
        Print Tab(38); Format$(DATA(NN2), "##.#####0");
        Print Tab(51); Format$(DATA(NN2 + 1), "##.#####0")
    Next I
End Sub