ERF or "error" function for testing.
        </li>
        <li>
          <b>ERFC_VALUES</b> returns some values of the ERFC or "complementary error" function for testing.
        </li>
        <li>
          <b>EULER_NUMBER_VALUES</b> returns some values of the Euler numbers.
        </li>
        <li>
          <b>EULER_POLY_VALUES</b> returns some values of the Euler polynomials.
        </li>
        <li>
          <b>EXP_VALUES</b> returns some values of the exponential function.
        </li>
        