Differentiation

One of the most common reasons for data smoothing is to then be able to differentiate the data.  As noted earlier in section \ref{201802}, one of the advantages of  using scipy.signal.savgol_filter is that the data smoothing and differentiation can be done in a single step (when working with evenly spaced data). Here is an example (for the data originally shown in Fig. \ref{987576}):