scipy/scipy — pull request #3042 by endolith (2013-11-05 15:21:26+00:00)
Title: DOC:Add freqz magnitude plotting example

Mention a callable that produces the expected plot

I don't know why this option even exists, though, if it doesn't produce what people expect. Maybe instead of this, the function itself should be modified to pass abs(h) in the first place?