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include/ECM/PHPExcel/Shared/JAMA/examples/polyfit.php

@@ -0,0 +1,73 @@
+<?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));
+?>