Or simply subtract a first-order fit. (What the matlab/numpy `detrend()` function does) Edit: I'll note that this is the same thing as subtracting a very long

Or simply subtract a first-order fit. (What the matlab/numpy `detrend()` function does) Edit: I'll note that this is the same thing as subtracting a very long-windowed low-pass filter, i.e., performing high-pass filtering.