n><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">-</span><span class="n">s</span>

<span class="w">   </span><span class="n">a</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">t</span>
<span class="w">   </span><span class="n">b</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">s</span>
<span class="k">end subroutine </span><span class="n">mat_rat</span>
<