function fftfiltbenchmark (kernel_length, N_fft)

  b  = rand (1,kernel_length);
  x  = rand (1e6,1);

  start = cputime ();
  y1  = filter (b, 1, x);
  printf ("filter cpu (s): %g\n", cputime () - start);

  start = cputime ();
  y2  = fftfilt (b, x, N_fft);
  printf ("fftfilt cpu (s): %g\n", cputime () - start);

  printf ("maximum discrepancy: %g\n", max (max (y1 - y2)));

end
