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src/lib/PHPExcel/Shared/trend/linearBestFitClass.php 3.29 KB
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  <?php
  /**
   * PHPExcel
   *
   * Copyright (c) 2006 - 2014 PHPExcel
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
   *
   * @category   PHPExcel
   * @package    PHPExcel_Shared_Trend
   * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
   * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL
   * @version    1.8.0, 2014-03-02
   */
  
  
  require_once(PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/bestFitClass.php');
  
  
  /**
   * PHPExcel_Linear_Best_Fit
   *
   * @category   PHPExcel
   * @package    PHPExcel_Shared_Trend
   * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
   */
  class PHPExcel_Linear_Best_Fit extends PHPExcel_Best_Fit
  {
  	/**
  	 * Algorithm type to use for best-fit
  	 * (Name of this trend class)
  	 *
  	 * @var	string
  	 **/
  	protected $_bestFitType		= 'linear';
  
  
  	/**
  	 * Return the Y-Value for a specified value of X
  	 *
  	 * @param	 float		$xValue			X-Value
  	 * @return	 float						Y-Value
  	 **/
  	public function getValueOfYForX($xValue) {
  		return $this->getIntersect() + $this->getSlope() * $xValue;
  	}	//	function getValueOfYForX()
  
  
  	/**
  	 * Return the X-Value for a specified value of Y
  	 *
  	 * @param	 float		$yValue			Y-Value
  	 * @return	 float						X-Value
  	 **/
  	public function getValueOfXForY($yValue) {
  		return ($yValue - $this->getIntersect()) / $this->getSlope();
  	}	//	function getValueOfXForY()
  
  
  	/**
  	 * Return the Equation of the best-fit line
  	 *
  	 * @param	 int		$dp		Number of places of decimal precision to display
  	 * @return	 string
  	 **/
  	public function getEquation($dp=0) {
  		$slope = $this->getSlope($dp);
  		$intersect = $this->getIntersect($dp);
  
  		return 'Y = '.$intersect.' + '.$slope.' * X';
  	}	//	function getEquation()
  
  
  	/**
  	 * Execute the regression and calculate the goodness of fit for a set of X and Y data values
  	 *
  	 * @param	 float[]	$yValues	The set of Y-values for this regression
  	 * @param	 float[]	$xValues	The set of X-values for this regression
  	 * @param	 boolean	$const
  	 */
  	private function _linear_regression($yValues, $xValues, $const) {
  		$this->_leastSquareFit($yValues, $xValues,$const);
  	}	//	function _linear_regression()
  
  
  	/**
  	 * Define the regression and calculate the goodness of fit for a set of X and Y data values
  	 *
  	 * @param	float[]		$yValues	The set of Y-values for this regression
  	 * @param	float[]		$xValues	The set of X-values for this regression
  	 * @param	boolean		$const
  	 */
  	function __construct($yValues, $xValues=array(), $const=True) {
  		if (parent::__construct($yValues, $xValues) !== False) {
  			$this->_linear_regression($yValues, $xValues, $const);
  		}
  	}	//	function __construct()
  
  }	//	class linearBestFit