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Dog slow, but does mixed radix!

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'make test' output :

### testing SNR for  1024 point FFTs
#### DOUBLE
snr_t2f = 295.52
snr_f2t = 307.98
#### FLOAT
snr_t2f = 144.62
snr_f2t = 143.23
#### SHORT
snr_t2f = -31.515
snr_f2t = -60.836

#### timing 10000 x 1024 point FFTs
#### DOUBLE
Elapsed:0:44.17 user:35.11 sys:0.27
#### FLOAT
Elapsed:0:24.22 user:19.66 sys:0.16
#### SHORT
Elapsed:0:30.39 user:25.07 sys:0.09
This commit is contained in:
Mark Borgerding
2003-10-11 02:21:48 +00:00
parent 08be1d86b4
commit 30c4ee30f5
2 changed files with 94 additions and 206 deletions
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6
fft.py
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@ -15,18 +15,22 @@ def fft(f):
else:
raise Exception('%s not factorable ' % n)
print 'n=%d,p=%d' % (n,p)
print f,' << fin'
m = n/p
Fout=[]
for q in range(p): # 0,1
fp = f[q::p]
print fp,'<< fp'
Fp = fft( fp )
Fout.extend( Fp )
for u in range(m):
scratch = Fout[u::m] # u to end in strides of m
print scratch
for q1 in range(p):
k = q1*m + u # indices to Fout above that became scratch
Fout[ k ] = scratch[0]
Fout[ k ] = scratch[0] # cuz e**0==1 in loop below
for q in range(1,p):
t = e ** ( j*2*pi*k*q/n )
Fout[ k ] += scratch[q] * t