Anywhere I saw a patch called "derivate". But I cannot find it again.
Has anybody an idea, where I should search for it?

M.

I have a homebrew version of it here:

http://www.dafe.lukifer.net/pdpatches/crazymachineredux/delta.pd

and in case you will be wondering, the integral function:

http://www.dafe.lukifer.net/pdpatches/crazymachineredux/undercurve.pd

Thank you sunji.