powerBestFitClass.php in Loft Data Grids 7.2

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vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/trend/powerBestFitClass.php

<?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    ##VERSION##, ##DATE##
 */
require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/bestFitClass.php';

/**
 * PHPExcel_Power_Best_Fit
 *
 * @category   PHPExcel
 * @package    PHPExcel_Shared_Trend
 * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_Power_Best_Fit extends PHPExcel_Best_Fit {

  /**
   * Algorithm type to use for best-fit
   * (Name of this trend class)
   *
   * @var	string
   **/
  protected $_bestFitType = 'power';

  /**
   * Return the Y-Value for a specified value of X
   *
   * @param	 float		$xValue			X-Value
   * @return	 float						Y-Value
   **/
  public function getValueOfYForX($xValue) {
    return $this
      ->getIntersect() * pow($xValue - $this->_Xoffset, $this
      ->getSlope());
  }

  //	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 pow(($yValue + $this->_Yoffset) / $this
      ->getIntersect(), 1 / $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 . ' * X^' . $slope;
  }

  //	function getEquation()

  /**
   * Return the Value of X where it intersects Y = 0
   *
   * @param	 int		$dp		Number of places of decimal precision to display
   * @return	 string
   **/
  public function getIntersect($dp = 0) {
    if ($dp != 0) {
      return round(exp($this->_intersect), $dp);
    }
    return exp($this->_intersect);
  }

  //	function getIntersect()

  /**
   * 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	$const
   */
  private function _power_regression($yValues, $xValues, $const) {
    foreach ($xValues as &$value) {
      if ($value < 0.0) {
        $value = 0 - log(abs($value));
      }
      elseif ($value > 0.0) {
        $value = log($value);
      }
    }
    unset($value);
    foreach ($yValues as &$value) {
      if ($value < 0.0) {
        $value = 0 - log(abs($value));
      }
      elseif ($value > 0.0) {
        $value = log($value);
      }
    }
    unset($value);
    $this
      ->_leastSquareFit($yValues, $xValues, $const);
  }

  //	function _power_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) {
      $this
        ->_power_regression($yValues, $xValues, $const);
    }
  }

}

//	class powerBestFit

Classes

Name	Description
PHPExcel_Power_Best_Fit	PHPExcel_Power_Best_Fit