Equi power graph

Here is my problem:

Say it that I have two variables vdd and vth and the function Ps(vdd,vth). I know the form of this function and I want to plot on the vdd-vth plane points with equal Ps (equi power line).

I can't figure how can I do this! Any advice?

Answer 1

[Vieniava]

check Contour plots out.