Is Zorro's BandPass filter the one that John Ehlers describes in Cycle Analytics for Traders? That is, does it account for spectral dilation by connecting a high pass filter an octave below the lower band?

I tried to check for myself, but I can't find the BandPass function in the file indicators.c Where is this function stored?

Thanks

AFAIK it's different to Ehler's filter, and licensed, i.e. not in indicators.c. It's a straight filter with no additional amplitude manipulation.