On the following graph:
Question:
Both custom implementations have delay while scipy's does not have. What's the trick?
Note: Custom implementations don't give the same result because they don't have the same coeff.
I'm using filtfilt function.
Based on Warren Weckesser comment, I went to documentation and it states that
This function applies a linear digital filter twice, once forward and once backwards. The combined filter has zero phase and a filter order twice that of the original.
https://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.filtfilt.html