elt top</span>
      <span class="c">! for identical matrix locations, a_elts are added</span>
      <span class="c">!-----------------------------------------------------</span>
      <span class="n">innz</span> <span class="o">=</span> <span class="mi">1</span>
      <span class="n">jj</span>  <span class="o">=</span> <span class="n">jptr</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>  <span class="c">! first non-zero element</span>
      <span class="n">jr1</span> <span c