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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 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">
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7 "HTML Tidy for Mac OS X (vers 1st December 2004), see www.w3.org">
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10
11 <title>Working with LTPDA objects (LTPDA Toolbox)</title>
12 <link rel="stylesheet" href="docstyle.css" type="text/css">
13 <meta name="generator" content="DocBook XSL Stylesheets V1.52.2">
14 <meta name="description" content=
15 "Presents an overview of the features, system requirements, and starting the toolbox.">
16 </head>
17
18 <body>
19 <a name="top_of_page" id="top_of_page"></a>
20
21 <p style="font-size:1px;">&nbsp;</p>
22
23 <table class="nav" summary="Navigation aid" border="0" width=
24 "100%" cellpadding="0" cellspacing="0">
25 <tr>
26 <td valign="baseline"><b>LTPDA Toolbox</b></td><td><a href="../helptoc.html">contents</a></td>
27
28 <td valign="baseline" align="right"><a href=
29 "objects_create.html"><img src="b_prev.gif" border="0" align=
30 "bottom" alt="Creating LTPDA Objects"></a>&nbsp;&nbsp;&nbsp;<a href=
31 "ao_intro.html"><img src="b_next.gif" border="0" align=
32 "bottom" alt="Analysis Objects"></a></td>
33 </tr>
34 </table>
35
36 <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Working with LTPDA objects</h1>
37 <hr>
38
39 <p>
40 <p>
41 The use of LTPDA objects requires some understanding of the nature of objects as implemented in MATLAB.
42 </p>
43 <p>
44 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>.
45 For convenience, the most important aspects in the context of LTPDA are reviewed below.
46 </p>
47 <p>
48 <ul>
49 <li>
50 <p><a href="objects_working.html#calling">Calling object methods</a></p>
51 </li>
52 <li>
53 <p><a href="objects_working.html#set">Setting object properties</a></p>
54 </li>
55 <li>
56 <p><a href="objects_working.html#copy">Copying objects</a></p>
57 </li>
58 <li><a href="objects_working.html#exploring">Exploring objects</a></li>
59 </ul>
60 </p>
61
62 <a name="calling" id= "calling"><h3 class="title">Calling object methods</h3></a>
63
64 <p>
65 Each class in LTPDA has a set of methods (functions) which can operate/act on instances of the class (objects).
66 For example, the AO class has a method <tt>psd</tt> which can compute the Power Spectral Density estimate of a
67 time-series AO.
68 </p>
69 <p>
70 To see which methods a particular class has, use the <tt>methods</tt> command. For example,
71 <div class="fragment"><pre>
72 >> methods(<span class="string">'ao'</span>)
73 </pre></div>
74 </p>
75 <p>
76 To call a method on an object, <tt>obj.method</tt>, or, <tt>method(obj)</tt>. For example,
77 <div class="fragment"><pre>
78 >> b = a.psd
79 </pre></div>
80 or
81 <div class="fragment"><pre>
82 >> b = psd(a)
83 </pre></div>
84 Additional arguments can be passed to the method (a <tt>plist</tt>, for example), as follows:
85 <div class="fragment"><pre>
86 >> b = a.psd(pl)
87 </pre></div>
88 or
89 <div class="fragment"><pre>
90 >> b = psd(a, pl)
91 </pre></div>
92 </p><br>
93 <p>
94 In order to pass multiple objects to a method, you must use the form
95 <div class="fragment"><pre>
96 >> b = psd(a1, a2, pl)
97 </pre></div>
98 </p><br>
99 <p>
100 Some methods can behave as modifiers which means that the object which the method acts on is modified. To
101 modify an object, just give no output. If we start with a time-series AO then modify it with the <tt>psd</tt>
102 method,
103 <div class="fragment"><pre>
104 >> a = ao(1:100, randn(100,1), 10)
105 >> a
106 M: running ao/display
107 ----------- ao 01: a -----------
108
109 name: None
110 data: (0,0.840375529753905) (0.1,-0.88803208232901) (0.2,0.100092833139322) (0.3,-0.544528929990548) (0.4,0.303520794649354) ...
111 -------- tsdata 01 ------------
112
113 fs: 10
114 x: [100 1], double
115 y: [100 1], double
116 dx: [0 0], double
117 dy: [0 0], double
118 xunits: [s]
119 yunits: []
120 nsecs: 10
121 t0: 1970-01-01 00:00:01.000
122 -------------------------------
123
124 hist: ao / ao / SId: fromVals ... -->$Id: ao .... S
125 mdlfile: empty
126 description:
127 UUID: 8cffab46-61f0-494a-af03-eb310aa76114
128 --------------------------------
129 </pre></div><br>
130 Then call the <tt>psd</tt> method:
131 <div class="fragment"><pre>
132 >> a.psd
133 M: running ao/psd
134 M: running ao/len
135 M: running ao/len
136 M: running ao/display
137 ----------- ao 01: PSD(a) -----------
138
139 name: PSD(a)
140 data: (0,0.117412356146407) (0.1,0.179893990497347) (0.2,0.173957816470448) (0.3,0.245076068355785) (0.4,0.213036543621994) ...
141 ----------- fsdata 01 -----------
142
143 fs: 10
144 x: [51 1], double
145 y: [51 1], double
146 dx: [0 0], double
147 dy: [0 0], double
148 xunits: [Hz]
149 yunits: [Hz^(-1)]
150 t0: 1970-01-01 00:00:01.000
151 navs: 1
152 ---------------------------------
153
154 hist: ao / psd / SId: psd.m,v 1.52 2009/09/05 05:57:32 mauro Exp S
155 mdlfile: empty
156 description:
157 UUID: 0d2395cd-22af-4645-a94c-69fa32c15982
158 -------------------------------------
159 </pre></div><br>
160 then the object <tt>a</tt> is converted to a frequency-series AO.
161 </p><br>
162 <p>
163 This modifier behaviour only works with certain methods, in particular, methods requiring more than one input object
164 will not behave as modifiers.
165 </p><br>
166 <a name="set" id= "set"><h3 class="title">Setting object properties</h3></a>
167 <p>
168 All object properties must be set using the appropriate setter method. For example, to set the name of a IIR filter
169 object,
170 <div class="fragment"><pre>
171 >> ii = miir();
172 >> ii.setName(<span class="string">'My Filter'</span>);
173 </pre></div>
174 </p>
175 <p>
176 Reading the value of a property is achieved by:
177 <div class="fragment"><pre>
178 >> ii.name
179
180 ans =
181
182 My Filter
183 </pre></div>
184 </p><br>
185
186 <a name="copy" id= "copy"><h3 class="title">Copying objects</h3></a>
187 <br>
188 <p>
189 Since all objects in LTPDA are handle objects, creating copies of objects needs to be done differently than in standard
190 MATLAB. For example,
191 <div class="fragment"><pre>
192 >> a = ao();
193 >> b = a;
194 </pre></div>
195 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
196 by the handle <tt>a</tt>. To see how this behaves,
197 <div class="fragment"><pre>
198 >> a = ao();
199 >> b = a;
200 >> b.setName(<span class="string">'My Name'</span>);
201 >> a.name
202
203 ans =
204
205 My Name
206 </pre></div>
207 </p>
208 <p>
209 Copying the object can be achieved using the copy constructor:
210 <div class="fragment"><pre>
211 >> a = ao();
212 >> b = ao(a);
213 >> b.setName(<span class="string">'My Name'</span>);
214 >> a.name
215
216 ans =
217
218 none
219 </pre></div>
220 <p>In this case, the variable <tt>b</tt> points to a new distinct copy of the object pointed to by <tt>a</tt>.
221 </p>
222 </p>
223 <p></p>
224 <h3 class="title"><a name="exploring" id="calling2">Exploring objects</a></h3>
225 <p> A browsing tool is provided on purpose to enable LTPDA objects exploring.</p>
226 <p><a href="gui_explorer.html">See the LTPDA Objects Explorer GUI documentation.</a></p>
227
228 </p>
229
230 <br>
231 <br>
232 <table class="nav" summary="Navigation aid" border="0" width=
233 "100%" cellpadding="0" cellspacing="0">
234 <tr valign="top">
235 <td align="left" width="20"><a href="objects_create.html"><img src=
236 "b_prev.gif" border="0" align="bottom" alt=
237 "Creating LTPDA Objects"></a>&nbsp;</td>
238
239 <td align="left">Creating LTPDA Objects</td>
240
241 <td>&nbsp;</td>
242
243 <td align="right">Analysis Objects</td>
244
245 <td align="right" width="20"><a href=
246 "ao_intro.html"><img src="b_next.gif" border="0" align=
247 "bottom" alt="Analysis Objects"></a></td>
248 </tr>
249 </table><br>
250
251 <p class="copy">&copy;LTP Team</p>
252 </body>
253 </html>