butterworth¶
- butterworth(dx, order, cutoff, /, btype='low')[source]¶
Applies Butterworth filter to data. Since this is a recursive filter, non-trivial to apply, so this uses scipy ‘lfilter’.
To get an ‘impulse response function’, pass a bunch of zeros with a single non-zero ‘point’ as the dx. See Libby’s function for more details.
- Parameters
dx (float) – Data spacing.
order (int) – Order of the filter.
cutoff (float) – Cutoff frequency in ‘x’ units (i.e. wavelengths).
- Returns
b (array-like) – Numerator coeffs.
a (array-like) – Denominator coeffs.