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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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1 <p>
2 The use of LTPDA objects requires some understanding of the nature of objects as implemented in MATLAB.
3 </p>
4 <p>
5 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>.
6 For convenience, the most important aspects in the context of LTPDA are reviewed below.
7 </p>
8 <p>
9 <ul>
10 <li>
11 <p><a href="objects_working.html#calling">Calling object methods</a></p>
12 </li>
13 <li>
14 <p><a href="objects_working.html#set">Setting object properties</a></p>
15 </li>
16 <li>
17 <p><a href="objects_working.html#copy">Copying objects</a></p>
18 </li>
19 <li><a href="objects_working.html#exploring">Exploring objects</a></li>
20 </ul>
21 </p>
22
23 <a name="calling" id= "calling"><h3 class="title">Calling object methods</h3></a>
24
25 <p>
26 Each class in LTPDA has a set of methods (functions) which can operate/act on instances of the class (objects).
27 For example, the AO class has a method <tt>psd</tt> which can compute the Power Spectral Density estimate of a
28 time-series AO.
29 </p>
30 <p>
31 To see which methods a particular class has, use the <tt>methods</tt> command. For example,
32 <div class="fragment"><pre>
33 >> methods(<span class="string">'ao'</span>)
34 </pre></div>
35 </p>
36 <p>
37 To call a method on an object, <tt>obj.method</tt>, or, <tt>method(obj)</tt>. For example,
38 <div class="fragment"><pre>
39 >> b = a.psd
40 </pre></div>
41 or
42 <div class="fragment"><pre>
43 >> b = psd(a)
44 </pre></div>
45 Additional arguments can be passed to the method (a <tt>plist</tt>, for example), as follows:
46 <div class="fragment"><pre>
47 >> b = a.psd(pl)
48 </pre></div>
49 or
50 <div class="fragment"><pre>
51 >> b = psd(a, pl)
52 </pre></div>
53 </p><br>
54 <p>
55 In order to pass multiple objects to a method, you must use the form
56 <div class="fragment"><pre>
57 >> b = psd(a1, a2, pl)
58 </pre></div>
59 </p><br>
60 <p>
61 Some methods can behave as modifiers which means that the object which the method acts on is modified. To
62 modify an object, just give no output. If we start with a time-series AO then modify it with the <tt>psd</tt>
63 method,
64 <div class="fragment"><pre>
65 >> a = ao(1:100, randn(100,1), 10)
66 >> a
67 M: running ao/display
68 ----------- ao 01: a -----------
69
70 name: None
71 data: (0,0.840375529753905) (0.1,-0.88803208232901) (0.2,0.100092833139322) (0.3,-0.544528929990548) (0.4,0.303520794649354) ...
72 -------- tsdata 01 ------------
73
74 fs: 10
75 x: [100 1], double
76 y: [100 1], double
77 dx: [0 0], double
78 dy: [0 0], double
79 xunits: [s]
80 yunits: []
81 nsecs: 10
82 t0: 1970-01-01 00:00:01.000
83 -------------------------------
84
85 hist: ao / ao / SId: fromVals ... -->$Id: ao .... S
86 mdlfile: empty
87 description:
88 UUID: 8cffab46-61f0-494a-af03-eb310aa76114
89 --------------------------------
90 </pre></div><br>
91 Then call the <tt>psd</tt> method:
92 <div class="fragment"><pre>
93 >> a.psd
94 M: running ao/psd
95 M: running ao/len
96 M: running ao/len
97 M: running ao/display
98 ----------- ao 01: PSD(a) -----------
99
100 name: PSD(a)
101 data: (0,0.117412356146407) (0.1,0.179893990497347) (0.2,0.173957816470448) (0.3,0.245076068355785) (0.4,0.213036543621994) ...
102 ----------- fsdata 01 -----------
103
104 fs: 10
105 x: [51 1], double
106 y: [51 1], double
107 dx: [0 0], double
108 dy: [0 0], double
109 xunits: [Hz]
110 yunits: [Hz^(-1)]
111 t0: 1970-01-01 00:00:01.000
112 navs: 1
113 ---------------------------------
114
115 hist: ao / psd / SId: psd.m,v 1.52 2009/09/05 05:57:32 mauro Exp S
116 mdlfile: empty
117 description:
118 UUID: 0d2395cd-22af-4645-a94c-69fa32c15982
119 -------------------------------------
120 </pre></div><br>
121 then the object <tt>a</tt> is converted to a frequency-series AO.
122 </p><br>
123 <p>
124 This modifier behaviour only works with certain methods, in particular, methods requiring more than one input object
125 will not behave as modifiers.
126 </p><br>
127 <a name="set" id= "set"><h3 class="title">Setting object properties</h3></a>
128 <p>
129 All object properties must be set using the appropriate setter method. For example, to set the name of a IIR filter
130 object,
131 <div class="fragment"><pre>
132 >> ii = miir();
133 >> ii.setName(<span class="string">'My Filter'</span>);
134 </pre></div>
135 </p>
136 <p>
137 Reading the value of a property is achieved by:
138 <div class="fragment"><pre>
139 >> ii.name
140
141 ans =
142
143 My Filter
144 </pre></div>
145 </p><br>
146
147 <a name="copy" id= "copy"><h3 class="title">Copying objects</h3></a>
148 <br>
149 <p>
150 Since all objects in LTPDA are handle objects, creating copies of objects needs to be done differently than in standard
151 MATLAB. For example,
152 <div class="fragment"><pre>
153 >> a = ao();
154 >> b = a;
155 </pre></div>
156 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
157 by the handle <tt>a</tt>. To see how this behaves,
158 <div class="fragment"><pre>
159 >> a = ao();
160 >> b = a;
161 >> b.setName(<span class="string">'My Name'</span>);
162 >> a.name
163
164 ans =
165
166 My Name
167 </pre></div>
168 </p>
169 <p>
170 Copying the object can be achieved using the copy constructor:
171 <div class="fragment"><pre>
172 >> a = ao();
173 >> b = ao(a);
174 >> b.setName(<span class="string">'My Name'</span>);
175 >> a.name
176
177 ans =
178
179 none
180 </pre></div>
181 <p>In this case, the variable <tt>b</tt> points to a new distinct copy of the object pointed to by <tt>a</tt>.
182 </p>
183 </p>
184 <p></p>
185 <h3 class="title"><a name="exploring" id="calling2">Exploring objects</a></h3>
186 <p> A browsing tool is provided on purpose to enable LTPDA objects exploring.</p>
187 <p><a href="gui_explorer.html">See the LTPDA Objects Explorer GUI documentation.</a></p>