the i-th row of the sparse 2d data structure</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment">//    MUDA_GENERIC Dense1D&lt;T&gt; operator()(int i) MUDA_NOEXCEPT</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment">//    {</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment">//        check_dimi(i);</span></d