<p> The LTPDA toolbox contains a class (<tt>pzmodel</tt>) for creating and using pole/zero models. The <it>pole/zero model helper GUI</it> allows the user to visualise the pole/zero model as it's being designed. It also allows the user to quickly see how the corresponding IIR filter (<tt>miir</tt> object) will look for different sample rates.</p> <p> To start the pole/zero model helper: <div class="fragment"> <pre> >> pzmodel_helper</pre> </div> or click the appropriate button on the LTPDA Launch Bay.</p><p> Once the GUI is loaded, you will see the following figure:</p><br><img src="images/pzmodel_helper.png" alt="pzmodel helper" border="3"><br><p> You can add poles and zeros to the model by entering the frequency (and Q) in the edit boxes, then click <tt>Add pole</tt> or <tt>Add zero</tt> as appropriate. The response is then updated in the response axes. </p><br><img src="images/pzmodel_helper_eg1.png" alt="pzmodel helper" border="3"><br>