diff --git a/src/PhpSpreadsheet/Shared/trend/trend.php b/src/PhpSpreadsheet/Shared/trend/trend.php
deleted file mode 100644
index 8979bf62..00000000
--- a/src/PhpSpreadsheet/Shared/trend/trend.php
+++ /dev/null
@@ -1,143 +0,0 @@
-<?php
-
-namespace PHPExcel\Shared\trend;
-
-/**
- * PHPExcel_\PHPExcel\Shared\trend\trend
- *
- * Copyright (c) 2006 - 2015 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 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
- * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
- * @version    ##VERSION##, ##DATE##
- */
-class trend
-{
-    const TREND_LINEAR            = 'Linear';
-    const TREND_LOGARITHMIC       = 'Logarithmic';
-    const TREND_EXPONENTIAL       = 'Exponential';
-    const TREND_POWER             = 'Power';
-    const TREND_POLYNOMIAL_2      = 'Polynomial_2';
-    const TREND_POLYNOMIAL_3      = 'Polynomial_3';
-    const TREND_POLYNOMIAL_4      = 'Polynomial_4';
-    const TREND_POLYNOMIAL_5      = 'Polynomial_5';
-    const TREND_POLYNOMIAL_6      = 'Polynomial_6';
-    const TREND_BEST_FIT          = 'Bestfit';
-    const TREND_BEST_FIT_NO_POLY  = 'Bestfit_no_Polynomials';
-
-    /**
-     * Names of the best-fit trend analysis methods
-     *
-     * @var string[]
-     **/
-    private static $trendTypes = array(
-        self::TREND_LINEAR,
-        self::TREND_LOGARITHMIC,
-        self::TREND_EXPONENTIAL,
-        self::TREND_POWER
-    );
-
-    /**
-     * Names of the best-fit trend polynomial orders
-     *
-     * @var string[]
-     **/
-    private static $trendTypePolynomialOrders = array(
-        self::TREND_POLYNOMIAL_2,
-        self::TREND_POLYNOMIAL_3,
-        self::TREND_POLYNOMIAL_4,
-        self::TREND_POLYNOMIAL_5,
-        self::TREND_POLYNOMIAL_6
-    );
-
-    /**
-     * Cached results for each method when trying to identify which provides the best fit
-     *
-     * @var bestFit[]
-     **/
-    private static $trendCache = array();
-
-
-    public static function calculate($trendType = self::TREND_BEST_FIT, $yValues, $xValues = array(), $const = true)
-    {
-        //    Calculate number of points in each dataset
-        $nY = count($yValues);
-        $nX = count($xValues);
-
-        //    Define X Values if necessary
-        if ($nX == 0) {
-            $xValues = range(1, $nY);
-            $nX = $nY;
-        } elseif ($nY != $nX) {
-            //    Ensure both arrays of points are the same size
-            trigger_error("trend(): Number of elements in coordinate arrays do not match.", E_USER_ERROR);
-        }
-
-        $key = md5($trendType.$const.serialize($yValues).serialize($xValues));
-        //    Determine which trend method has been requested
-        switch ($trendType) {
-            //    Instantiate and return the class for the requested trend method
-            case self::TREND_LINEAR:
-            case self::TREND_LOGARITHMIC:
-            case self::TREND_EXPONENTIAL:
-            case self::TREND_POWER:
-                if (!isset(self::$trendCache[$key])) {
-                    $className = '\PHPExcel\Shared\trend\\'.strtolower($trendType).'BestFit';
-                    self::$trendCache[$key] = new $className($yValues, $xValues, $const);
-                }
-                return self::$trendCache[$key];
-            case self::TREND_POLYNOMIAL_2:
-            case self::TREND_POLYNOMIAL_3:
-            case self::TREND_POLYNOMIAL_4:
-            case self::TREND_POLYNOMIAL_5:
-            case self::TREND_POLYNOMIAL_6:
-                if (!isset(self::$trendCache[$key])) {
-                    $order = substr($trendType, -1);
-                    self::$trendCache[$key] = new polynomialBestFit($order, $yValues, $xValues, $const);
-                }
-                return self::$trendCache[$key];
-            case self::TREND_BEST_FIT:
-            case self::TREND_BEST_FIT_NO_POLY:
-                //    If the request is to determine the best fit regression, then we test each trend line in turn
-                //    Start by generating an instance of each available trend method
-                foreach (self::$trendTypes as $trendMethod) {
-                    $className = '\PHPExcel\Shared\trend\\'.strtolower($trendType).'BestFit';
-                    $bestFit[$trendMethod] = new $className($yValues, $xValues, $const);
-                    $bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
-                }
-                if ($trendType != self::TREND_BEST_FIT_NO_POLY) {
-                    foreach (self::$trendTypePolynomialOrders as $trendMethod) {
-                        $order = substr($trendMethod, -1);
-                        $bestFit[$trendMethod] = new polynomialBestFit($order, $yValues, $xValues, $const);
-                        if ($bestFit[$trendMethod]->getError()) {
-                            unset($bestFit[$trendMethod]);
-                        } else {
-                            $bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
-                        }
-                    }
-                }
-                //    Determine which of our trend lines is the best fit, and then we return the instance of that trend class
-                arsort($bestFitValue);
-                $bestFitType = key($bestFitValue);
-                return $bestFit[$bestFitType];
-            default:
-                return false;
-        }
-    }
-}