<p>
  Transfer functions can be expressed as a quocient of polynomials as in the following expression
</p>
<br>
<div align="center">
  <img src="images/rational_tf_eqn.png" alt="Pole/zero model TF" border="3">
</div>
<br>
<p>
  The constructor can be used in different ways
</p>
<h2>From coefficients</a></h2>
<p>
  The standard way is to input the coefficients of your filter. The constructor
  accepts as a optional properties the name
</p>
<br>
<div class="fragment"><pre>
    >> rat   = rational([1 3 5 7],[5 10 0.01],'filter_name')
    ---- rational 1 ----
    model:    filter_name
    num:      [1 3 5 7]
    den:      [5 10 0.01]
    iunits:   []
    ounits:   []
    --------------------
</pre></div>
<br>
<h2>From partial XML file</a></h2>
You can input a XML file containing a transfer function model into the constructor
<br>
<div class="fragment"><pre>
    >> rat   = rational('datafile.xml')
</pre></div>
<br>
<h2>From mat file</a></h2>
You can input a mat file containing a transfer function model into the constructor
<br>
<div class="fragment"><pre>
    >> rat   = rational('datafile.mat')
</pre></div>
<br>
<h2>From plist</a></h2>
All the properties of the filter can be specified in a plist and then passed to the constructor:
<br>
<div class="fragment"><pre>
    >> pl = plist('iunits','m','ounits','V','num',[1 3 10],'den',[4 6],...
    'name','filter_mame');
    >> par   = parfrac(pl)
    ---- rational 1 ----
    model:    filter_mame
    num:      [1 3 10]
    den:      [4 6]
    iunits:   [m]
    ounits:   [V]
    --------------------
</pre></div>
<br>
<h2>From repository</a></h2>
Rational transfer function can be obtained from the <a href="repo.html"> repository </a> with the following syntax.
<br>
<div class="fragment"><pre>
    >> rat   = rational('Hostname','localhost','Database','ltpda',...
    'ID',[],'CID',[],'Binary',yes)
</pre></div>
<br>