N=100
lowX=-3
highX=3
for i=1:N
    for j=1:N
        x(i,j)=lowX+i*(highX-lowX)/N;
        y(i,j)=lowX+j*(highX-lowX)/N;
        z(i,j)=cos(x(i,j).^2+y(i,j).^2);
    end
end