e>
<span></span><span class="sd">&quot;&quot;&quot;**Description**</span>
<span class="sd">    A complex frequency filter adapts and discriminates the phase of a forward</span>
<span class="sd">    complex coefficient to produce a reference signal, which estimates a normalized</span>
<span class="sd">    frequency of a primary signal which is normalized to unity magnitude.  A</span>
<span class="sd">    normalized frequency and rate of adaptation are specified.</span>

<span class="sd">    .. math::</span>
