eters for problem 30.
        </li>
        <li>
          <a href = "p30_region.m">p30_region.m</a>, 
          returns the region type for problem 30.
        </li>
        <li>
          <a href = "p30_title.m">p30_title.m</a>, 
          prints a title for problem 30.
        </li>
        <li>
          <a href = "p31_default.m">p31_default.m</a>, 
          sets default values for problem 31.
        </li>
        <li>
          <a href = "p31_exact.m">p31_exact.m</a>, 
          sets the exact integr