<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> <meta http-equiv="X-UA-Compatible" content="IE=9"/> <title>Variance Example</title> <title>CMSIS-DSP: Variance Example</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <link href="cmsis.css" rel="stylesheet" type="text/css" /> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript" src="dynsections.js"></script> <script type="text/javascript" src="printComponentTabs.js"></script> <link href="navtree.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="resize.js"></script> <script type="text/javascript" src="navtree.js"></script> <script type="text/javascript"> $(document).ready(initResizable); $(window).load(resizeHeight); </script> <link href="search/search.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="search/search.js"></script> <script type="text/javascript"> $(document).ready(function() { searchBox.OnSelectItem(0); }); </script> </head> <body> <div id="top"><!-- do not remove this div, it is closed by doxygen! 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Uniformly distributed white noise is taken as input.</dd></dl> <dl class="section user"><dt>Algorithm:</dt><dd></dd></dl> <dl class="section user"><dt></dt><dd>The variance of a sequence is the mean of the squared deviation of the sequence from its mean. </dd></dl> <dl class="section user"><dt></dt><dd>This is denoted by the following equation: <pre> variance = ((x[0] - x') * (x[0] - x') + (x[1] - x') * (x[1] - x') + ... + * (x[n-1] - x') * (x[n-1] - x')) / (N-1)</pre> where, <code>x[n]</code> is the input sequence, <code>N</code> is the number of input samples, and <code>x'</code> is the mean value of the input sequence, <code>x[n]</code>. </dd></dl> <dl class="section user"><dt></dt><dd>The mean value <code>x'</code> is defined as: <pre> x' = (x[0] + x[1] + ... + x[n-1]) / N</pre></dd></dl> <dl class="section user"><dt>Block Diagram:</dt><dd></dd></dl> <dl class="section user"><dt></dt><dd><div class="image"> <img src="Variance.gif" alt="Variance.gif"/> </div> </dd></dl> <dl class="section user"><dt>Variables Description:</dt><dd></dd></dl> <dl class="section user"><dt></dt><dd><ul> <li><code>testInput_f32</code> points to the input data </li> <li><code>wire1</code>, <code>wir2</code>, <code>wire3</code> temporary buffers </li> <li><code>blockSize</code> number of samples processed at a time </li> <li><code>refVarianceOut</code> reference variance value</li> </ul> </dd></dl> <dl class="section user"><dt>CMSIS DSP Software Library Functions Used:</dt><dd></dd></dl> <dl class="section user"><dt></dt><dd><ul> <li><a class="el" href="group__dot__prod.html#ga55418d4362f6ba84c327f9b4f089a8c3" title="Dot product of floating-point vectors. ">arm_dot_prod_f32()</a></li> <li><a class="el" href="group__BasicMult.html#gaca3f0b8227da431ab29225b88888aa32" title="Floating-point vector multiplication. ">arm_mult_f32()</a></li> <li><a class="el" href="group__BasicSub.html#ga7f975a472de286331134227c08aad826" title="Floating-point vector subtraction. ">arm_sub_f32()</a></li> <li><a class="el" href="group__Fill.html#ga2248e8d3901b4afb7827163132baad94" title="Fills a constant value into a floating-point vector. ">arm_fill_f32()</a></li> <li><a class="el" href="group__copy.html#gadd1f737e677e0e6ca31767c7001417b3" title="Copies the elements of a floating-point vector. ">arm_copy_f32()</a></li> </ul> </dd></dl> <p><b> Refer </b> <a class="el" href="arm_variance_example_f32_8c-example.html">arm_variance_example_f32.c</a> </p> </div><!-- contents --> </div><!-- doc-content --> <!-- start footer part --> <div id="nav-path" class="navpath"><!-- id is needed for treeview function! --> <ul> <li class="footer">Generated on Wed Feb 8 2017 10:20:51 for CMSIS-DSP by ARM Ltd. All rights reserved. <!-- <a href="http://www.doxygen.org/index.html"> <img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.8.6 --> </li> </ul> </div> </body> </html>