16,472
社区成员
发帖
与我相关
我的任务
分享关于反傅立叶变换
哪位老兄有反傅立叶变换的程序呀，贴出来看看好吗，或者发到我人信箱里面
tigersky2000@163.com
先谢了
tigersky2000@163.com
先谢了
...全文
请发表友善的回复…
发表回复
lwglucky 2002-07-31
- 打赏
- 举报
Sub FFT(n, xr(), xi(), inv)
Dim m, nv2, nm1, tr, TI
Dim i, j, k, l, le, le1, ip As Integer
Dim ur, ui, wr, wi, ur1, ui1
m = Log(n) / Log(2#) + 0.1
nv2 = n / 2: nm1 = n - 1
j = 1
For i = 1 To nm1
If i < j Then
tr = xr(j): TI = xi(j)
xr(j) = xr(i): xi(j) = xi(i)
xr(i) = tr: xi(i) = TI
End If
k = nv2
Do While k < j
j = j - k: k = k / 2
Loop
j = j + k
Next i
For l = 1 To m
le = 2 ^ l: le1 = le / 2
ur = 1#: ui = 0#
wr = Cos(PI / le1): wi = -Sin(PI / le1)
If inv <> 0 Then wi = Sin(PI / le1)
For j = 1 To le1
For i = j To n Step le
ip = i + le1
tr = xr(ip) * ur - xi(ip) * ui
TI = xr(ip) * ui + xi(ip) * ur
xr(ip) = xr(i) - tr
xi(ip) = xi(i) - TI
xr(i) = xr(i) + tr
xi(i) = xi(i) + TI
Next i
ur1 = ur * wr - ui * wi
ui1 = ur * wi + ui * wr
ur = ur1
ui = ui1
Next j
Next l
If inv <> 0 Then
For i = 1 To n
xr(i) = xr(i) / n: xi(i) = xi(i) / n
Next i
End If
End Sub
---------------------------------
UNFFT---没有
Dim m, nv2, nm1, tr, TI
Dim i, j, k, l, le, le1, ip As Integer
Dim ur, ui, wr, wi, ur1, ui1
m = Log(n) / Log(2#) + 0.1
nv2 = n / 2: nm1 = n - 1
j = 1
For i = 1 To nm1
If i < j Then
tr = xr(j): TI = xi(j)
xr(j) = xr(i): xi(j) = xi(i)
xr(i) = tr: xi(i) = TI
End If
k = nv2
Do While k < j
j = j - k: k = k / 2
Loop
j = j + k
Next i
For l = 1 To m
le = 2 ^ l: le1 = le / 2
ur = 1#: ui = 0#
wr = Cos(PI / le1): wi = -Sin(PI / le1)
If inv <> 0 Then wi = Sin(PI / le1)
For j = 1 To le1
For i = j To n Step le
ip = i + le1
tr = xr(ip) * ur - xi(ip) * ui
TI = xr(ip) * ui + xi(ip) * ur
xr(ip) = xr(i) - tr
xi(ip) = xi(i) - TI
xr(i) = xr(i) + tr
xi(i) = xi(i) + TI
Next i
ur1 = ur * wr - ui * wi
ui1 = ur * wi + ui * wr
ur = ur1
ui = ui1
Next j
Next l
If inv <> 0 Then
For i = 1 To n
xr(i) = xr(i) / n: xi(i) = xi(i) / n
Next i
End If
End Sub
---------------------------------
UNFFT---没有
