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| <dl class="section user"><dt>Description:</dt><dd></dd></dl> |
| <dl class="section user"><dt></dt><dd>Demonstrates the use of Basic Math and Support Functions to calculate the variance of an input sequence with N samples. 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> |
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| <img src="Variance.gif" alt="Variance.gif"/> |
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| <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__BasicDotProd.html#gadf26f6bc62d6416528663ad3e46fbf67" title="Dot product of floating-point vectors. ">arm_dot_prod_f32()</a></li> |
| <li><a class="el" href="group__BasicMult.html#gacf950935141cad927bea886e88fd9e9b" title="Floating-point vector multiplication. ">arm_mult_f32()</a></li> |
| <li><a class="el" href="group__BasicSub.html#ga76b8b2aec34269c6de0b090cab00fb33" 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#gaa6dfe9554ca61eb3d1eee498396bce88" 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> |
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