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Mark Borgerding 2003-11-14 04:20:19 +00:00
parent 63e7df14cf
commit 164ab47a25
1 changed files with 0 additions and 15 deletions
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15
fft.py
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@ -17,19 +17,15 @@ def fft(f,inv):
else: else:
raise Exception('%s not factorable ' % n) raise Exception('%s not factorable ' % n)
#print 'n=%d,p=%d' % (n,p)
#print f,' << fin'
m = n/p m = n/p
Fout=[] Fout=[]
for q in range(p): # 0,1 for q in range(p): # 0,1
fp = f[q::p] fp = f[q::p]
#print fp,'<< fp'
Fp = fft( fp ,inv) Fp = fft( fp ,inv)
Fout.extend( Fp ) Fout.extend( Fp )
for u in range(m): for u in range(m):
scratch = Fout[u::m] # u to end in strides of m scratch = Fout[u::m] # u to end in strides of m
#print scratch
for q1 in range(p): for q1 in range(p):
k = q1*m + u # indices to Fout above that became scratch k = q1*m + u # indices to Fout above that became scratch
Fout[ k ] = scratch[0] # cuz e**0==1 in loop below Fout[ k ] = scratch[0] # cuz e**0==1 in loop below
@ -50,8 +46,6 @@ def rifft(F):
Fok = ( F[k] - F[-k-1].conjugate() ) * e ** (j*pi*k/N) Fok = ( F[k] - F[-k-1].conjugate() ) * e ** (j*pi*k/N)
Z[k] = Fek + j*Fok Z[k] = Fek + j*Fok
#print 'Z', Z
fp = fft(Z , 1) fp = fft(Z , 1)
f = [] f = []
@ -71,7 +65,6 @@ def real_fft( f,inv ):
fp = [ complex(r,i) for r,i in zip(res,ims) ] fp = [ complex(r,i) for r,i in zip(res,ims) ]
Fp = fft( fp ,0 ) Fp = fft( fp ,0 )
#print 'F=',Fp
F = [] F = []
for k in range(N): for k in range(N):
@ -83,14 +76,6 @@ def real_fft( f,inv ):
F.append( complex( Fp[0].real - Fp[0].imag , 0 ) ) F.append( complex( Fp[0].real - Fp[0].imag , 0 ) )
return F return F
def test(f=range(1024),ntimes=10):
import time
t0 = time.time()
for i in range(ntimes):
fft(f,0)
t1 = time.time()
print '%ss'% (t1-t0)
def main(): def main():
#fft_func = fft #fft_func = fft
fft_func = real_fft fft_func = real_fft