format long e
a=0;
b=1;
n=64;
h=(b-a)/n;
g=@(x) a+h*x;
f=@(x) exp(-x);

s1=0;
for j=1:n/2
  s1=s1+f(g(2*j-1));
end

s2=0;
for j=1:n/2-1
  s2=s2+f(g(2*j));
end

t=h/3*(f(0)+4*s1+2*s2+f(1));
t