function integral = trap(f,a,b,n)

%a and b = initial and last point of integral
%n = number of intervals

answer=0;
h = (b-a)/n;
x=(a+h:h:b-h);
for i=1:n-1
    answer = answer + f(x(i));
end
answer=h*(answer+0.5*(f(a)+f(b)));
integral=answer;
end