fft_time.c  Athlon 1.4GHz XP professional
N=16 FFT time=1.95e-006 
     inv time=2.75e-006 
    both time=4.3e-006 

N=32 FFT time=4.65e-006 
     inv time=6.25e-006 
    both time=1.015e-005 

N=64 FFT time=1.1e-005 
     inv time=1.4e-005 
    both time=2.19e-005 

N=128 FFT time=2.82e-005 
     inv time=2.5e-005 
    both time=5.3e-005 

N=256 FFT time=5.64e-005 
     inv time=5.64e-005 
    both time=0.0001124 

N=512 FFT time=0.000124 
     inv time=0.000158 
    both time=0.00025 

N=1024 FFT time=0.000248 
     inv time=0.000312 
    both time=0.0005 

N=2048 FFT time=0.000625 
     inv time=0.00055 
    both time=0.00117 

N=4096 FFT time=0.00141 
     inv time=0.00125 
    both time=0.00234