会vb编程的高手请进

dragoon0114

小弟不会编程，故在网上找，但只有源代码。我看我老师做的好象随便什么函数都可以的。
拜托高人能帮我把程序注释一下，解释一下这样编程的原理更好。如果能加上已编好的样例程序那就完美了。
程序如下：
'*模块********************************************************
'FFT0 数组下标以0开始 FFT1 数组下标以1开始
'AR() 数据实部         AI() 数据虚部
'N 数据点数，为2的整数次幂
'NI 变换方向 1为正变换，-1为反变换
'***************************************************************

Public Const Pi = 3.1415926

Public Function FFT0(AR() As Double, AI() As Double, N As Integer, ni As Integer)
    Dim i As Integer, j As Integer, k As Integer, L As Integer, M As Integer
    Dim IP As Integer, LE As Integer
    Dim L1 As Integer, N1 As Integer, N2 As Integer
    Dim SN As Double, TR As Double, TI As Double, WR As Double, WI As Double
    Dim UR As Double, UI As Double, US As Double
    M = NTOM(N)
    N2 = N / 2
    N1 = N - 1
    SN = ni
    j = 1
    For i = 1 To N1
        If i < j Then
            TR = AR(j - 1)
            AR(j - 1) = AR(i - 1)
            AR(i - 1) = TR
            TI = AI(j - 1)
            AI(j - 1) = AI(i - 1)
            AI(i - 1) = TI
        End If
        k = N2
        While (k < j)
            j = j - k
            k = k / 2
        Wend
        j = j + k
    Next i
    For L = 1 To M
        LE = 2 ^ L
        L1 = LE / 2
        UR = 1#
        UI = 0#
        WR = Cos(Pi / L1)
        WI = SN * Sin(Pi / L1)
        For j = 1 To L1
            For i = j To N Step LE
                IP = i + L1
                TR = AR(IP - 1) * UR - AI(IP - 1) * UI
                TI = AI(IP - 1) * UR + AR(IP - 1) * UI
                AR(IP - 1) = AR(i - 1) - TR
                AI(IP - 1) = AI(i - 1) - TI
                AR(i - 1) = AR(i - 1) + TR
                AI(i - 1) = AI(i - 1) + TI
            Next i
            US = UR
            UR = US * WR - UI * WI
            UI = UI * WR + US * WI
        Next j
    Next L
    If SN <> -1 Then
        For i = 1 To N
            AR(i - 1) = AR(i - 1) / N
            AI(i - 1) = AI(i - 1) / N
        Next i
    End If
End Function

Public Function FFT1(AR() As Double, AI() As Double, N As Integer, ni As Integer)
    Dim i As Integer, j As Integer, k As Integer, L As Integer, M As Integer
    Dim IP As Integer, LE As Integer
    Dim L1 As Integer, N1 As Integer, N2 As Integer
    Dim SN As Double, TR As Double, TI As Double, WR As Double, WI As Double
    Dim UR As Double, UI As Double, US As Double
    M = NTOM(N)
    N2 = N / 2
    N1 = N - 1
    SN = ni
    j = 1
    For i = 1 To N1
        If i < j Then
            TR = AR(j)
            AR(j) = AR(i)
            AR(i) = TR
            TI = AI(j)
            AI(j) = AI(i)
            AI(i) = TI
        End If
        k = N2
        While (k < j)
            j = j - k
            k = k / 2
        Wend
        j = j + k
    Next i
    For L = 1 To M
        LE = 2 ^ L
        L1 = LE / 2
        UR = 1#
        UI = 0#
        WR = Cos(Pi / L1)
        WI = SN * Sin(Pi / L1)
        For j = 1 To L1
            For i = j To N Step LE
                IP = i + L1
                TR = AR(IP) * UR - AI(IP) * UI
                TI = AI(IP) * UR + AR(IP) * UI
                AR(IP) = AR(i) - TR
                AI(IP) = AI(i) - TI
                AR(i) = AR(i) + TR
                AI(i) = AI(i) + TI
            Next i
            US = UR
            UR = US * WR - UI * WI
            UI = UI * WR + US * WI
        Next j
    Next L
    If SN <> -1 Then
        For i = 1 To N
            AR(i) = AR(i) / N
            AI(i) = AI(i) / N
        Next i
    End If
End Function

Private Function NTOM(N As Integer) As Integer
    Dim ND As Double
    ND = N
    NTOM = 0
    While (ND > 1)
        ND = ND / 2
        NTOM = NTOM + 1
    Wend
End Function

'*使用**********

    Const fftIn = 128
    Dim i As Integer
    Dim xr(128) As Double
    Dim xi(128) As Double

'赋值，IaIn(i)是采得的数据。   
    For i = 0 To 128
    xr(i) = 100 * IaIn(i)
    xi(i) = 0
    Next

'FFT变换
    Call FFT0(xr(), xi(), 128, 1)

'绘图
    picI_FFT.Scale (0, 100)-(fftIn - 1, -10)
    picI_FFT.DrawWidth = 2
    For i = 0 To fftIn - 1
    picI_FFT.Line (i, Abs(xr(i)))-(i + 1, Abs(xr(i + 1))), vbBlue
    Next i

dragoon0114

如果有类似编程的网站请介绍给我，谢谢！

dragoon0114

我反变换不需要，关键在复数和算法