We have a function which describes a frequency response correction to piezo devices we use. To flatten the FFT, it is similar to: Cdis_t = .5 N = 8192 for n in range(8192): B3 = n * 2560 / N Fc(n) = 1 / ((B3/((1/(Cdis_t*2*pi))**2+B3**2)**0.5)*(-0.01*log(B3) + 1.04145)) In practice it really only matters for low frequencies. I suggested that we might be able to do a time domain correction as a forward-reverse FFT filter using the function, but another said it can also be applied in the time domain using a bilinear transform. So, can one use http://docs.scipy.org/doc/scipy-0.16.0/reference/generated/scipy.signal.bili... and, how does one generate b,a from the given Fourrier domain flattening function? I'd guess someone here has done this... - Ray