"n"><span class="pre">fmax</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#utils.df_spec" title="Permalink to this definition">¶</a></dt>
<dd><p>Dual frequency spectrum using one/two MTSPEC classes. 
For now, only positive frequencies are studied</p>
<p>Construct the dual-frequency spectrum from the yk’s and the 
weights of the usual multitaper spectrum estimatio