FFT.rar_FFT-VB_basic and fft_fft vb_vb fft_vb fft 引用

'*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