ubtracts two C4's.
        </li>
        <li>
          <b>C4_SWAP</b> swaps two C4's.
        </li>
        <li>
          <b>C4_TAN</b> evaluates the tangent of a C4.
        </li>
        <li>
          <b>C4_TANH</b> evaluates the hyperbolic tangent of a C4.
        </li>
        <li>
          <b>C4_TO_CARTESIAN</b> converts a C4 to Cartesian form.
        </li>
        <li>
          <b>C4_TO_POLAR</b> converts a C4 to polar form.
        </li>
        <li>
          <b>C4_UNIFORM_01</b> returns a uni