mirror of
https://github.com/mborgerding/kissfft.git
synced 2025-06-03 00:58:12 -04:00
44 lines
884 B
Python
44 lines
884 B
Python
#!/usr/local/bin/python2.3
|
|
import math
|
|
pi=math.pi
|
|
e=math.e
|
|
j=complex(0,1)
|
|
|
|
def fft(f):
|
|
n=len(f)
|
|
if n==1:
|
|
return f
|
|
|
|
for p in 2,3,5:
|
|
if n%p==0:
|
|
break
|
|
else:
|
|
raise Exception('%s not factorable ' % n)
|
|
|
|
m = n/p
|
|
Fout=[]
|
|
for q in range(p): # 0,1
|
|
fp = f[q::p]
|
|
Fp = fft( fp )
|
|
Fout.extend( Fp )
|
|
|
|
for u in range(m):
|
|
scratch = Fout[u::m] # u to end in strides of m
|
|
for q1 in range(p):
|
|
k = q1*m + u # indices to Fout above that became scratch
|
|
Fout[ k ] = scratch[0]
|
|
for q in range(1,p):
|
|
t = e ** ( j*2*pi*k*q/n )
|
|
Fout[ k ] += scratch[q] * t
|
|
|
|
return Fout
|
|
|
|
def test(f=range(1024),ntimes=10):
|
|
import time
|
|
t0 = time.time()
|
|
for i in range(ntimes):
|
|
fft(f)
|
|
t1 = time.time()
|
|
print '%ss'% (t1-t0)
|
|
|