the boundary conditions;
        </li>
        <li>
          <a href = "initial_condition.m">initial_condition.m</a>,
          the user-supplied routines to evaluate the initial conditions;
        </li>
        <li>
          <a href = "k_coef.m">k_coef.m</a>,
          the user-supplied routines to evaluate the linear coefficient.
        </li>
        <li>
          <a href = "rhs.m">rhs.m</a>,
          the user-supplied routines to evaluate the right hand side;
        </li>
        <li>
          <a