<?php
/**
* @author Michele Andreoli <michi.andreoli@gmail.com>
* @name index.php
* @version 0.3 updated 06-07-2010
* @license http://opensource.org/licenses/gpl-license-php GNU Public License
* @package Noise
*/
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Noise</title>
</head>
<body>
<?php
require_once 'Noise.class.php';
require_once 'FFT.class.php';
require_once 'Filter.class.php';
// Define a sinuosoidal function
$f = array();
$f[0] = 0;
for ($i = 1; $i < 512; $i++) {
$f[$i] = sin(2 * M_PI / 512 * $i);
}
// Define a exponential function
$g = array();
$index = 0;
for ($i = -200.0; $i < 200.0; $i += 400.0 / 512) {
$g[$index] = 1 + (2 * sqrt(pow(200.0, 2.0) - pow($i, 2.0)));
$index++;
}
$noise = new Noise();
$filter = new Filter();
$fft = new FFT(512);
// Add gaussian noise in the sinusoidal function
$f = $noise->addGaussian($f, 0, 0.1);
// Add poissonian noise in the exponential function
$g = $noise->addPoisson($g);
// Calculate the FFT of function f with gaussian noise
$f = $fft->getAbsFFT($fft->fft($f));
// Remove the high frequency (noise)
$f = $filter->filterLP($f, 1);
// Calculate the inverse FFT of function f, and return the original signal f
$f = $fft->ifft($fft->doubleToComplex($f));
$f = $fft->complexToDouble($f);
for ($i = 0; $i < count($f); $i++)
echo $f[$i]."<br/>";
?>
</body>
</html>
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