C</span> <span class="nv">must</span>
        <span class="nv">contain</span> <span class="nv">the</span> <span class="nv">matrix</span> <span class="nv">C</span>, <span class="nv">except</span> <span class="nv">when</span> <span class="nv">beta</span> <span class="nv">is</span> <span class="nv">zero</span>, <span class="nv">in</span> <span class="nv">which</span>
        <span class="nv">case</span> <span class="nv">C</span> <span class="nv">need</span> <span class="nv">not</span> <span class="nv">be</span