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https://github.com/mborgerding/kissfft.git
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30c4ee30f5
'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
48 lines
1011 B
Python
48 lines
1011 B
Python
#!/usr/local/bin/python2.3
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import math
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pi=math.pi
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e=math.e
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j=complex(0,1)
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def fft(f):
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n=len(f)
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if n==1:
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return f
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for p in 2,3,5:
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if n%p==0:
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break
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else:
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raise Exception('%s not factorable ' % n)
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print 'n=%d,p=%d' % (n,p)
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print f,' << fin'
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m = n/p
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Fout=[]
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for q in range(p): # 0,1
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fp = f[q::p]
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print fp,'<< fp'
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Fp = fft( fp )
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Fout.extend( Fp )
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for u in range(m):
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scratch = Fout[u::m] # u to end in strides of m
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print scratch
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for q1 in range(p):
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k = q1*m + u # indices to Fout above that became scratch
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Fout[ k ] = scratch[0] # cuz e**0==1 in loop below
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for q in range(1,p):
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t = e ** ( j*2*pi*k*q/n )
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Fout[ k ] += scratch[q] * t
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return Fout
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def test(f=range(1024),ntimes=10):
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import time
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t0 = time.time()
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for i in range(ntimes):
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fft(f)
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t1 = time.time()
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print '%ss'% (t1-t0)
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