I've also tried using .measure deriv, and I can get the derivative at a specific value but not a waveform output or the maximum/minimum of the derivative

I also tried to do this in Xyce, without success. The ddx(f(x),x) function is supposed to do that, however i also was unable to get a waveform with it. I tried to that in xschem, see below.

Thanks! I'll post in the google group and see if the Xyce team is aware