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src/lib/PHPExcel/Shared/trend/linearBestFitClass.php 3.39 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