format long
n = 64;
a = 0;
b = 1;
h = (b-a)/n;
C = 1:n+1;
C(1) = 1;
C(n+1) = 1;
C(2:2:n) = 4;
C(3:2:n-1) = 2;
ans = 0;
x = a;
for(i = 1 : n+1)
  ans = exp(-x)*C(i) + ans;
  x = x+h;
 end
 ans = ans*h/3;
 ans