Warren, I currently have two functions, Nyquist and rootNyquist, that return the coefficients of a nyquist or root-nyquist filter with a specified alpha and length. The algorithm that the functions implement is one proposed by Fred Harris in hist multi-rate signal processing book. It uses the remez algorithm to start as an initial guess and uses a gradient descent method to adjust the cutoff frequency of the passband until the filter's 3 dB (or 6 dB) point is at half the baud rate. I think the API that you mentioned for the Savitzky-Golay filter uses sounds simple and effective. What are ideas of how to test this? I can think of writing some simple unit tests that check filter length, gain, etc. Would that be sufficient. Here is a link to my github project for the code so far: https://github.com/fstop22/nyquist_filters Thanks, Jeff