PHPExcel

# Source for file polyfit.php Documentation is available at polyfit.php <?php require_once "../Matrix.php"; /* * @package JAMA * @author Michael Bommarito * @author Paul Meagher * @version 0.1 * * Function to fit an order n polynomial function through * a series of x-y data points using least squares. * * @param $X array x values * @param $Y array y values * @param $n int order of polynomial to be used for fitting * @returns array $coeffs of polynomial coefficients * Pre-Conditions: the system is not underdetermined: sizeof($X) > $n+1 */ function polyfit($X, $Y, $n) { for ($i = 0; $i < sizeof($X); ++$i) for ($j = 0; $j <= $n; ++$j) $A[$i][$j] = pow($X[$i], $j); for ($i=0; $i < sizeof($Y); ++$i) $B[$i] = array($Y[$i]); $matrixA = new Matrix($A); $matrixB = new Matrix($B); $C = $matrixA->solve($matrixB); return $C->getMatrix(0, $n, 0, 1); } function printpoly( $C = null ) { for($i = $C->m - 1; $i >= 0; --$i) { $r = $C->get($i, 0); if ( abs($r) <= pow(10, -9) ) $r = 0; if ($i == $C->m - 1) echo $r . "x<sup>$i</sup>"; else if ($i < $C->m - 1) echo " + " . $r . "x<sup>$i</sup>"; else if ($i == 0) echo " + " . $r; } } $X = array(0,1,2,3,4,5); $Y = array(4,3,12,67,228, 579); $points = new Matrix(array($X, $Y)); $points->toHTML(); printpoly(polyfit($X, $Y, 4)); echo '<hr />'; $X = array(0,1,2,3,4,5); $Y = array(1,2,5,10,17, 26); $points = new Matrix(array($X, $Y)); $points->toHTML(); printpoly(polyfit($X, $Y, 2)); echo '<hr />'; $X = array(0,1,2,3,4,5,6); $Y = array(-90,-104,-178,-252,-26, 1160, 4446); $points = new Matrix(array($X, $Y)); $points->toHTML(); printpoly(polyfit($X, $Y, 5)); echo '<hr />'; $X = array(0,1,2,3,4); $Y = array(mt_rand(0, 10), mt_rand(40, 80), mt_rand(240, 400), mt_rand(1800, 2215), mt_rand(8000, 9000)); $points = new Matrix(array($X, $Y)); $points->toHTML(); printpoly(polyfit($X, $Y, 3)); ?> Documentation generated on Sun, 27 Feb 2011 16:33:27 -0800 by phpDocumentor 1.4.3