          sets or gets R8VEC parameters for problem 27.
        </li>
        <li>
          <a href = "p27_region.m">p27_region.m</a>, 
          returns the region type for problem 27.
        </li>
        <li>
          <a href = "p27_title.m">p27_title.m</a>, 
          prints a title for problem 27.
        </li>
        <li>
          <a href = "p28_default.m">p28_default.m</a>, 
          sets default values for problem 28.
        </li>
        <li>
          <a href = "p28_exact.m">p28_exact.m</a>