GA Optimization with considering limitation

Hi all

I want to optimize an analytic surface equation [for example :f(x,y)=C1*cos(a1*x)cos(b1*y)+C2*cos(a2*x)*cos(b2*y)+... which C1,C2 should be optimized ] that on this surface, a function [ like: fun(f(x,y),xx1,xx2,... ] should have minimum value. But a limitation for f(x,y) should be considered [ max(f(x,y))< h_max ] . How can I do that ?