root/doc/html/mexfiles.html @ 324

Revision 323, 5.6 kB (checked in by smidl, 16 years ago)

doc

Line 
1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
2<html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
3<title>mixpp: How to write and use mex files for Matlab</title>
4<link href="tabs.css" rel="stylesheet" type="text/css">
5<link href="doxygen.css" rel="stylesheet" type="text/css">
6</head><body>
7<!-- Generated by Doxygen 1.5.8 -->
8<script type="text/javascript">
9<!--
10function changeDisplayState (e){
11  var num=this.id.replace(/[^[0-9]/g,'');
12  var button=this.firstChild;
13  var sectionDiv=document.getElementById('dynsection'+num);
14  if (sectionDiv.style.display=='none'||sectionDiv.style.display==''){
15    sectionDiv.style.display='block';
16    button.src='open.gif';
17  }else{
18    sectionDiv.style.display='none';
19    button.src='closed.gif';
20  }
21}
22function initDynSections(){
23  var divs=document.getElementsByTagName('div');
24  var sectionCounter=1;
25  for(var i=0;i<divs.length-1;i++){
26    if(divs[i].className=='dynheader'&&divs[i+1].className=='dynsection'){
27      var header=divs[i];
28      var section=divs[i+1];
29      var button=header.firstChild;
30      if (button!='IMG'){
31        divs[i].insertBefore(document.createTextNode(' '),divs[i].firstChild);
32        button=document.createElement('img');
33        divs[i].insertBefore(button,divs[i].firstChild);
34      }
35      header.style.cursor='pointer';
36      header.onclick=changeDisplayState;
37      header.id='dynheader'+sectionCounter;
38      button.src='closed.gif';
39      section.id='dynsection'+sectionCounter;
40      section.style.display='none';
41      section.style.marginLeft='14px';
42      sectionCounter++;
43    }
44  }
45}
46window.onload = initDynSections;
47-->
48</script>
49<div class="navigation" id="top">
50  <div class="tabs">
51    <ul>
52      <li><a href="main.html"><span>Main&nbsp;Page</span></a></li>
53      <li class="current"><a href="pages.html"><span>Related&nbsp;Pages</span></a></li>
54      <li><a href="modules.html"><span>Modules</span></a></li>
55      <li><a href="annotated.html"><span>Classes</span></a></li>
56      <li><a href="files.html"><span>Files</span></a></li>
57    </ul>
58  </div>
59  <div class="navpath"><a class="el" href="manual.html">User Manual</a>
60  </div>
61</div>
62<div class="contents">
63<h1><a class="anchor" name="mexfiles">How to write and use mex files for Matlab </a></h1><h2><a class="anchor" name="use">
64Howto use predefined mexfiles</a></h2>
65A range of mexfiles is predefined in directory <code>library/mex</code>. Many of these mexfile process ui files (see <a class="el" href="ui.html">User Infos and their use</a>) examples of these files are in directory <code>library/tutorial</code>. Note that in order to run these files you need to let matlab know where to find them: <div class="fragment"><pre class="fragment">&gt;&gt; addpath path_to_bdm/library/mex
66</pre></div><p>
67Then, you can go to <code>library/tutorial</code> and run e.g. <code>arx_test_mex</code>.<h2><a class="anchor" name="write">
68Howto write custom mex file</a></h2>
69Due to special nature of the mex files, the mex file can be split in three parts: <ul>
70<li>input conversion, where input arguments are converted to IT++ structures, </li>
71<li>main body of algorithm, where any C++ bdm constructions can be used, </li>
72<li>output conversion, where resulting IT++ structures are converted to mxArrays.</li>
73</ul>
74The first and the third part is achieved using prepared IT++ routines, see IT++ documentation.<p>
75Script <code></code>./buildmex is prepared to compile and link the mexfile with bdm. <div class="fragment"><pre class="fragment">$ ./buildmex.sh my_mex_file.cpp
76</pre></div> on Linux, or <div class="fragment"><pre class="fragment">$ ./buildmex.bat my_mex_file.cpp
77</pre></div> on Windows.<p>
78Example of a mexfile: <div class="fragment"><pre class="fragment"><span class="preprocessor">#include &lt;itpp/itmex.h&gt;</span>
79<span class="preprocessor">#include &lt;<a class="code" href="arx_8h.html" title="Bayesian Filtering for generalized autoregressive (ARX) model.">estim/arx.h</a>&gt;</span>
80
81<span class="keyword">using namespace </span>bdm;
82
83<span class="keywordtype">void</span> mexFunction(<span class="keywordtype">int</span> n_output, mxArray *output[], <span class="keywordtype">int</span> n_input, <span class="keyword">const</span> mxArray *input[])
84{
85    <span class="comment">// Check the number of inputs and output arguments</span>
86        <span class="keywordflow">if</span>(n_output!=1) mexErrMsgTxt(<span class="stringliteral">"Wrong number of output variables!"</span>);
87        <span class="keywordflow">if</span>(n_input!=2) mexErrMsgTxt(<span class="stringliteral">"Usage: arx1d(ysize, Data)!"</span>);
88
89    <span class="comment">// Convert input variables to IT++ format</span>
90        <span class="keywordtype">int</span> ysize = mxArray2int(input[0]);
91        mat Data = mxArray2mat(input[1]);
92
93    <span class="comment">// ------------------ Start of routine ---------------------------</span>
94        ARX Ar;
95        Ar.set_statistics(ysize, 1e-5*eye(Data.rows()) );
96        Ar.bayesB(Data);
97        <span class="comment">// ------------------ End of routine -----------------------------</span>
98
99    <span class="comment">// Create output vectors</span>
100        output[0] = mxCreateDoubleMatrix(1,Data.rows(), mxREAL);
101
102    <span class="comment">// Convert the IT++ format to Matlab format for output</span>
103        vec2mxArray(Ar.posterior().mean(), output[0]);
104}
105</pre></div> </div>
106<hr size="1"><address style="text-align: right;"><small>Generated on Thu Apr 23 21:06:43 2009 for mixpp by&nbsp;
107<a href="http://www.doxygen.org/index.html">
108<img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.8 </small></address>
109</body>
110</html>
Note: See TracBrowser for help on using the browser.