bad jacobians can cause the Newton convergence
      to become linear rather than quadratic.
      <ul>
        <li>
          <a href = "pitcon66_prb6.f">pitcon66_prb6.f</a>,
          a sample calling program.
        </li>
        <li>
          <a href = "pitcon66_prb6.sh">pitcon66_prb6.sh</a>,
          commands to compile and run the sample program.
        </li>
        <li>
          <a href = "pitcon66_prb6_output.txt">pitcon66_prb6_output.txt</a>,
          the output file.
        </li>
      </u