Hi, I would like know if it is possible to tell which function is better over another? For instance, I have two functions: (i) f(x,y)=exp(a*x) * exp(b*y) (ii) f(x,y)=a(exp(x)) * b(exp(y)) I would like to know the characteristics of both the functions which make it better/less better over another. (e.g.: the effect of a and b towards the results; the complexity or etc.) I've tried plotting the functions in 3D graphs, but didn't help much.. Please guide. Thanks in advance!