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+<p>
+  The use of LTPDA objects requires some understanding of the nature of objects as implemented in MATLAB.
+</p>
+<p>
+  For full details of objects in MATLAB, refer to <a href="matlab:web(['jar:file:///' matlabroot '/help/techdoc/help.jar!/matlab_oop/ug_intropage.html'])">MATLAB Classes and Object-Oriented Programming</a>.
+  For convenience, the most important aspects in the context of LTPDA are reviewed below.
+</p>
+<p>
+  <ul>
+    <li>
+      <p><a href="objects_working.html#calling">Calling object methods</a></p>
+    </li>
+    <li>
+      <p><a href="objects_working.html#set">Setting object properties</a></p>
+    </li>
+    <li>
+      <p><a href="objects_working.html#copy">Copying objects</a></p>
+    </li>
+    <li><a href="objects_working.html#exploring">Exploring objects</a></li>
+  </ul>
+</p>
+
+<a name="calling" id= "calling"><h3 class="title">Calling object methods</h3></a>
+
+<p>
+  Each class in LTPDA has a set of methods (functions) which can operate/act on instances of the class (objects).
+  For example, the AO class has a method <tt>psd</tt> which can compute the Power Spectral Density estimate of a
+  time-series AO.
+</p>
+<p>
+  To see which methods a particular class has, use the <tt>methods</tt> command. For example,
+  <div class="fragment"><pre>
+      >> methods(<span class="string">'ao'</span>)
+  </pre></div>
+</p>
+<p>
+  To call a method on an object, <tt>obj.method</tt>, or, <tt>method(obj)</tt>. For example,
+  <div class="fragment"><pre>
+      >> b = a.psd
+  </pre></div>
+  or
+  <div class="fragment"><pre>
+      >> b = psd(a)
+  </pre></div>
+  Additional arguments can be passed to the method (a <tt>plist</tt>, for example), as follows:
+  <div class="fragment"><pre>
+      >> b = a.psd(pl)
+  </pre></div>
+  or
+  <div class="fragment"><pre>
+      >> b = psd(a, pl)
+  </pre></div>
+</p><br>
+<p>
+  In order to pass multiple objects to a method, you must use the form
+  <div class="fragment"><pre>
+      >> b = psd(a1, a2, pl)
+  </pre></div>
+</p><br>
+<p>
+  Some methods can behave as modifiers which means that the object which the method acts on is modified. To
+  modify an object, just give no output. If we start with a time-series AO then modify it with the <tt>psd</tt>
+  method,
+  <div class="fragment"><pre>
+      >> a = ao(1:100, randn(100,1), 10)
+      >> a
+       M:   running ao/display
+      ----------- ao 01: a -----------
+      
+             name:  None
+             data: (0,0.840375529753905) (0.1,-0.88803208232901) (0.2,0.100092833139322) (0.3,-0.544528929990548) (0.4,0.303520794649354) ...
+                   -------- tsdata 01 ------------
+              
+                       fs:  10
+                        x:  [100 1], double
+                        y:  [100 1], double
+                       dx:  [0 0], double
+                       dy:  [0 0], double
+                   xunits:  [s]
+                   yunits:  []
+                    nsecs:  10
+                       t0:  1970-01-01 00:00:01.000
+                   -------------------------------
+              
+             hist:  ao / ao / SId: fromVals ... -->$Id: ao .... S
+          mdlfile:  empty
+      description:  
+             UUID:  8cffab46-61f0-494a-af03-eb310aa76114
+      --------------------------------
+  </pre></div><br>
+  Then call the <tt>psd</tt> method:
+  <div class="fragment"><pre>
+      >> a.psd
+       M:   running ao/psd
+       M:   running ao/len
+       M:   running ao/len
+       M:   running ao/display
+      ----------- ao 01: PSD(a) -----------
+ 
+             name:  PSD(a)
+             data: (0,0.117412356146407) (0.1,0.179893990497347) (0.2,0.173957816470448) (0.3,0.245076068355785) (0.4,0.213036543621994) ...
+                   ----------- fsdata 01 -----------
+              
+                       fs:  10
+                        x:  [51 1], double
+                        y:  [51 1], double
+                       dx:  [0 0], double
+                       dy:  [0 0], double
+                   xunits:  [Hz]
+                   yunits:  [Hz^(-1)]
+                       t0:  1970-01-01 00:00:01.000
+                     navs:  1
+                   ---------------------------------
+              
+             hist:  ao / psd / SId: psd.m,v 1.52 2009/09/05 05:57:32 mauro Exp S
+          mdlfile:  empty
+      description:  
+             UUID:  0d2395cd-22af-4645-a94c-69fa32c15982
+      -------------------------------------
+  </pre></div><br>
+  then the object <tt>a</tt> is converted to a frequency-series AO.
+</p><br>
+<p>
+  This modifier behaviour only works with certain methods, in particular, methods requiring more than one input object
+  will not behave as modifiers.
+</p><br>
+<a name="set" id= "set"><h3 class="title">Setting object properties</h3></a>
+<p>
+  All object properties must be set using the appropriate setter method. For example, to set the name of a IIR filter
+  object,
+  <div class="fragment"><pre>
+      >> ii = miir();
+      >> ii.setName(<span class="string">'My Filter'</span>);
+  </pre></div>
+</p>
+<p>
+  Reading the value of a property is achieved by:
+  <div class="fragment"><pre>
+      >> ii.name
+
+      ans =
+
+      My Filter
+  </pre></div>
+</p><br>
+
+<a name="copy" id= "copy"><h3 class="title">Copying objects</h3></a>
+<br>
+<p>
+  Since all objects in LTPDA are handle objects, creating copies of objects needs to be done differently than in standard
+  MATLAB. For example,
+  <div class="fragment"><pre>
+      >> a = ao();
+      >> b = a;
+  </pre></div>
+  in this case, the variable <tt>b</tt> is a copy of the handle <tt>a</tt>, not a copy of the object pointed too
+  by the handle <tt>a</tt>. To see how this behaves,
+  <div class="fragment"><pre>
+      >> a = ao();
+      >> b = a;
+      >> b.setName(<span class="string">'My Name'</span>);
+      >> a.name
+
+      ans =
+
+      My Name
+  </pre></div>
+</p>
+<p>
+  Copying the object can be achieved using the copy constructor:
+  <div class="fragment"><pre>
+      >> a = ao();
+      >> b = ao(a);
+      >> b.setName(<span class="string">'My Name'</span>);
+      >> a.name
+
+      ans =
+
+      none
+  </pre></div>
+  <p>In this case, the variable <tt>b</tt> points to a new distinct copy of the object pointed to by <tt>a</tt>.
+    </p>
+</p>
+  <p></p>
+<h3 class="title"><a name="exploring" id="calling2">Exploring objects</a></h3>
+  <p> A browsing tool is provided on purpose to enable LTPDA objects exploring.</p>
+  <p><a href="gui_explorer.html">See the LTPDA Objects Explorer GUI documentation.</a></p>