 <span class="comment">% if present, copy starting point</span>
0040   <span class="keyword">if</span> (isfield(pen,<span class="string">'x0'</span>))
0041     <span class="keyword">if</span> (isempty(pen.x0) || ~isvector(pen.x0) || length(pen.x0)~=Nx)
0042       error(<span class="string">'Input: starting point x0 is incompatible.'</span>);
0043     <span class="keyword">end</span>
0044     bmidata.xinit = pen.x0;
0045   <span class="keyword">end</span>
0046 
0047   <span class="comment">% dense vector of 