function y=f1(x)
  y=x(1)+x(2);//f(x,y)=x+y
endfunction


N=10
U=rand(2,N)

a=[1; -1]
b=[5; 3]

X=(a+(b-a)*0.5)

y=f1(X)
z=f1(a+(b-a).*[0.5; 0.2])

  S=0
  for i=1:N
    S=S+f1(a+(b-a).*U(:,i));
  end
S