function t = comptrap(f,a,b,n)
%
%  DESCRIPTION :
%    Returns the value of the composite trapezoidal rule to
%    approximate the integral of f over [a,b], using n intervals.
%
h = (b-a)/n;   % step size
t = (feval(f,a)+feval(f,b))*h/2;  % for n = 1
for i=1:n-1
    t = t+h*feval(f,a+i*h);
end