format long
n = 64;
h = 1/n;
x = 0:h:1;
f = exp(-x);
w = ones(1,65);
w(2:2:n) = 4;
w(3:2:n-1) = 2;
s = w*f'*h/3
exact = 1-exp(-1)
err = (exact-s)/exact