 values for problem 04.
        </li>
        <li>
          <a href = "p04_exact.m">p04_exact.m</a>, 
          sets the exact integral for problem 04.
        </li>
        <li>
          <a href = "p04_f.m">p04_f.m</a>, 
          evaluates the integrand for problem 04.
        </li>
        <li>
          <a href = "p04_i4.m">p04_i4.m</a>, 
          sets or gets I4 parameters for problem 04.
        </li>
        <li>
          <a href = "p04_lim.m">p04_lim.m</a>, 
          returns the integration lim