ositions ( x,z )</span>
0007 
0008 N.elec=[];SP=1;
0009 <span class="keyword">if</span> nargin&gt;1,
0010     input=fopen(<span class="string">'data/rothdi.dat'</span>,<span class="string">'r'</span>);
0011 <span class="keyword">else</span>
0012     input=fopen(datafile,<span class="string">'r'</span>);
0013 <span class="keyword">end</span>
0014 <span class="keyword">if</span> input&lt;0, 
0015     message(sprintf(<span class="string">'Could not open datafile: %s'</span>,datafile));
0016     <span class="ke