/branches/v1.6.5/Classes/PHPExcel/Calculation/Functions.php

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<?php

/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2009 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_Calculation
 * @copyright  Copyright (c) 2006 - 2009 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license	http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL
 * @version	##VERSION##, ##DATE##
 */


define('EPS', 2.22e-16);
define('MAX_VALUE', 1.2e308);
define('LOG_GAMMA_X_MAX_VALUE', 2.55e305);
define('SQRT2PI', 2.5066282746310005024157652848110452530069867406099);
define('XMININ', 2.23e-308);
define('MAX_ITERATIONS', 150);
define('PRECISION', 8.88E-016);
define('EULER', 2.71828182845904523536);

$savedPrecision = ini_get('precision');
if ($savedPrecision < 15) {
	ini_set('precision',15);
}


/** PHPExcel_Cell */
require_once 'PHPExcel/Cell.php';

/** PHPExcel_Cell_DataType */
require_once 'PHPExcel/Cell/DataType.php';

/** PHPExcel_Shared_Date */
require_once 'PHPExcel/Shared/Date.php';

/** PHPExcel_Shared_Date */
require_once 'PHPExcel/Shared/JAMA/Matrix.php';


/**
 * PHPExcel_Calculation_Functions
 *
 * @category   PHPExcel
 * @package	PHPExcel_Calculation
 * @copyright  Copyright (c) 2006 - 2009 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_Calculation_Functions {

	/** constants */
	const COMPATIBILITY_EXCEL		= 'Excel';
	const COMPATIBILITY_GNUMERIC	= 'Gnumeric';
	const COMPATIBILITY_OPENOFFICE	= 'OpenOfficeCalc';

	const RETURNDATE_PHP_NUMERIC = 'P';
	const RETURNDATE_PHP_OBJECT = 'O';
	const RETURNDATE_EXCEL = 'E';


	/**
	 * Compatibility mode to use for error checking and responses
	 *
	 * @var string
	 */
	private static $compatibilityMode	= self::COMPATIBILITY_EXCEL;

	/**
	 * Data Type to use when returning date values
	 *
	 * @var integer
	 */
	private static $ReturnDateType	= self::RETURNDATE_PHP_NUMERIC;

	/**
	 * List of error codes
	 *
	 * @var array
	 */
	private static $_errorCodes	= array( 'null'				=> '#NULL!',
										 'divisionbyzero'	=> '#DIV/0!',
										 'value'			=> '#VALUE!',
										 'reference'		=> '#REF!',
										 'name'				=> '#NAME?',
										 'num'				=> '#NUM!',
										 'na'				=> '#N/A',
										 'gettingdata'		=> '#GETTING_DATA'
									   );


	/**
	 * Set the Compatibility Mode
	 *
	 * @param	 string		$compatibilityMode		Compatibility Mode
	 * @return	 boolean	(Success or Failure)
	 */
	public static function setCompatibilityMode($compatibilityMode) {
		if (($compatibilityMode == self::COMPATIBILITY_EXCEL) ||
			($compatibilityMode == self::COMPATIBILITY_GNUMERIC) ||
			($compatibilityMode == self::COMPATIBILITY_OPENOFFICE)) {
			self::$compatibilityMode = $compatibilityMode;
			return True;
		}
		return False;
	}

	/**
	 * Return the current Compatibility Mode
	 *
	 * @return	 string		$compatibilityMode		Compatibility Mode
	 */
	public static function getCompatibilityMode() {
		return self::$compatibilityMode;
	}

	/**
	 * Set the Return Date Format (Excel, PHP Serialized or PHP Object)
	 *
	 * @param	 integer	$returnDateType			Return Date Format
	 * @return	 boolean							Success or failure
	 */
	public static function setReturnDateType($returnDateType) {
		if (($returnDateType == self::RETURNDATE_PHP_NUMERIC) ||
			($returnDateType == self::RETURNDATE_PHP_OBJECT) ||
			($returnDateType == self::RETURNDATE_EXCEL)) {
			self::$ReturnDateType = $returnDateType;
			return True;
		}
		return False;
	}	//	function setReturnDateType()


	/**
	 * Return the Return Date Format (Excel, PHP Serialized or PHP Object)
	 *
	 * @return	 integer	$returnDateType			Return Date Format
	 */
	public static function getReturnDateType() {
		return self::$ReturnDateType;
	}	//	function getReturnDateType()


	/**
	 * DUMMY
	 *
	 * @return  string	#NAME?
	 */
	public static function DUMMY() {
		return self::$_errorCodes['name'];
	}

	/**
	 * NA
	 *
	 * @return  string	#N/A!
	 */
	public static function NA() {
		return self::$_errorCodes['na'];
	}

	/**
	 * LOGICAL_AND
	 *
	 * Returns boolean TRUE if all its arguments are TRUE; returns FALSE if one or more argument is FALSE.
	 *
	 *	Booleans arguments are treated as True or False as appropriate
	 *	Integer or floating point arguments are treated as True, except for 0 or 0.0 which are False
	 *	If any argument value is a string, or a Null, it is ignored
	 *
	 *	Quirk of Excel:
	 *		String values passed directly to the function rather than through a cell reference
	 *			e.g.=AND(1,"A",1)
	 *		will return a #VALUE! error, _not_ ignoring the string.
	 *		This behaviour is not replicated
	 *
	 * @param	array of mixed		Data Series
	 * @return  boolean
	 */
	public static function LOGICAL_AND() {
		// Return value
		$returnValue = True;

		// Loop through the arguments
		$aArgs = self::flattenArray(func_get_args());
		$argCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a boolean value?
			if (is_bool($arg)) {
				$returnValue = $returnValue && $arg;
				++$argCount;
			} elseif ((is_numeric($arg)) && (!is_string($arg))) {
				$returnValue = $returnValue && ($arg != 0);
				++$argCount;
			}
		}

		// Return
		if ($argCount == 0) {
			return self::$_errorCodes['value'];
		}
		return $returnValue;
	}

	/**
	 * LOGICAL_OR
	 *
	 * Returns boolean TRUE if any argument is TRUE; returns FALSE if all arguments are FALSE.
	 *
	 *	Booleans arguments are treated as True or False as appropriate
	 *	Integer or floating point arguments are treated as True, except for 0 or 0.0 which are False
	 *	If any argument value is a string, or a Null, it is ignored
	 *
	 * @param	array of mixed		Data Series
	 * @return  boolean
	 */
	public static function LOGICAL_OR() {
		// Return value
		$returnValue = False;

		// Loop through the arguments
		$aArgs = self::flattenArray(func_get_args());
		$argCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a boolean value?
			if (is_bool($arg)) {
				$returnValue = $returnValue || $arg;
				++$argCount;
			} elseif ((is_numeric($arg)) && (!is_string($arg))) {
				$returnValue = $returnValue || ($arg != 0);
				++$argCount;
			}
		}

		// Return
		if ($argCount == 0) {
			return self::$_errorCodes['value'];
		}
		return $returnValue;
	}

	/**
	 * LOGICAL_FALSE
	 *
	 * Returns FALSE.
	 *
	 * @return  boolean
	 */
	public static function LOGICAL_FALSE() {
		return False;
	}

	/**
	 * LOGICAL_TRUE
	 *
	 * Returns TRUE.
	 *
	 * @return  boolean
	 */
	public static function LOGICAL_TRUE() {
		return True;
	}

	/**
	 * ATAN2
	 *
	 * This function calculates the arc tangent of the two variables x and y. It is similar to
	 *		calculating the arc tangent of y / x, except that the signs of both arguments are used
	 *		to determine the quadrant of the result.
	 * Note that Excel reverses the arguments, so we need to reverse them here before calling the
	 *		standard PHP atan() function
	 *
	 * @param	float	$x		Number
	 * @param	float	$y		Number
	 * @return  float	Square Root of Number * Pi
	 */
	public static function REVERSE_ATAN2($x, $y) {
		$x	= self::flattenSingleValue($x);
		$y	= self::flattenSingleValue($y);

		return atan2($y, $x);
	}

	/**
	 * SUM
	 *
	 * SUM computes the sum of all the values and cells referenced in the argument list.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function SUM() {
		// Return value
		$returnValue = 0;

		// Loop through the arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				$returnValue += $arg;
			}
		}

		// Return
		return $returnValue;
	}

	/**
	 * SUMSQ
	 *
	 * Returns the sum of the squares of the arguments
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function SUMSQ() {
		// Return value
		$returnValue = 0;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				$returnValue += pow($arg,2);
			}
		}

		// Return
		return $returnValue;
	}

	/**
	 * PRODUCT
	 *
	 * PRODUCT returns the product of all the values and cells referenced in the argument list.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function PRODUCT() {
		// Return value
		$returnValue = null;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				if (is_null($returnValue)) {
					$returnValue = $arg;
				} else {
					$returnValue *= $arg;
				}
			}
		}

		// Return
		if (is_null($returnValue)) {
			return 0;
		}
		return $returnValue;
	}

	/**
	 * QUOTIENT
	 *
	 * QUOTIENT function returns the integer portion of a division.numerator is the divided number
	 * and denominator is the divisor.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function QUOTIENT() {
		// Return value
		$returnValue = null;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				if (is_null($returnValue)) {
					if (($returnValue == 0) || ($arg == 0)) {
						$returnValue = 0;
					} else {
						$returnValue = $arg;
					}
				} else {
					if (($returnValue == 0) || ($arg == 0)) {
						$returnValue = 0;
					} else {
						$returnValue /= $arg;
					}
				}
			}
		}

		// Return
		return intval($returnValue);
	}

	/**
	 * MIN
	 *
	 * MIN returns the value of the element of the values passed that has the smallest value,
	 * with negative numbers considered smaller than positive numbers.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MIN() {
		// Return value
		$returnValue = null;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				if ((is_null($returnValue)) || ($arg < $returnValue)) {
					$returnValue = $arg;
				}
			}
		}

		// Return
		if(is_null($returnValue)) {
			return 0;
		}
		return $returnValue;
	}

	/**
	 * MINA
	 *
	 * Returns the smallest value in a list of arguments, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MINA() {
		// Return value
		$returnValue = null;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) && ($arg != '')))) {
				if (is_bool($arg)) {
					$arg = (integer) $arg;
				} elseif (is_string($arg)) {
					$arg = 0;
				}
				if ((is_null($returnValue)) || ($arg < $returnValue)) {
					$returnValue = $arg;
				}
			}
		}

		// Return
		if(is_null($returnValue)) {
			return 0;
		}
		return $returnValue;
	}

	/**
	 * SMALL
	 *
	 * Returns the nth smallest value in a data set. You can use this function to
	 * select a value based on its relative standing.
	 *
	 * @param	array of mixed		Data Series
	 * @param	float	Entry in the series to return
	 * @return	float
	 */
	public static function SMALL() {
		$aArgs = self::flattenArray(func_get_args());

		// Calculate
		$n = array_pop($aArgs);

		if ((is_numeric($n)) && (!is_string($n))) {
			$mArgs = array();
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					$mArgs[] = $arg;
				}
			}
			$count = self::COUNT($mArgs);
			$n = floor(--$n);
			if (($n < 0) || ($n >= $count) || ($count == 0)) {
				return self::$_errorCodes['num'];
			}
			sort($mArgs);
			return $mArgs[$n];
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * MAX
	 *
	 * MAX returns the value of the element of the values passed that has the highest value,
	 * with negative numbers considered smaller than positive numbers.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MAX() {
		// Return value
		$returnValue = null;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				if ((is_null($returnValue)) || ($arg > $returnValue)) {
					$returnValue = $arg;
				}
			}
		}

		// Return
		if(is_null($returnValue)) {
			return 0;
		}
		return $returnValue;
	}

	/**
	 * MAXA
	 *
	 * Returns the greatest value in a list of arguments, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MAXA() {
		// Return value
		$returnValue = null;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) && ($arg != '')))) {
				if (is_bool($arg)) {
					$arg = (integer) $arg;
				} elseif (is_string($arg)) {
					$arg = 0;
				}
				if ((is_null($returnValue)) || ($arg > $returnValue)) {
					$returnValue = $arg;
				}
			}
		}

		// Return
		if(is_null($returnValue)) {
			return 0;
		}
		return $returnValue;
	}

	/**
	 * LARGE
	 *
	 * Returns the nth largest value in a data set. You can use this function to
	 * select a value based on its relative standing.
	 *
	 * @param	array of mixed		Data Series
	 * @param	float	Entry in the series to return
	 * @return	float
	 *
	 */
	public static function LARGE() {
		$aArgs = self::flattenArray(func_get_args());

		// Calculate
		$n = floor(array_pop($aArgs));

		if ((is_numeric($n)) && (!is_string($n))) {
			$mArgs = array();
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					$mArgs[] = $arg;
				}
			}
			$count = self::COUNT($mArgs);
			$n = floor(--$n);
			if (($n < 0) || ($n >= $count) || ($count == 0)) {
				return self::$_errorCodes['num'];
			}
			rsort($mArgs);
			return $mArgs[$n];
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * PERCENTILE
	 *
	 * Returns the nth percentile of values in a range..
	 *
	 * @param	array of mixed		Data Series
	 * @param	float	$entry		Entry in the series to return
	 * @return	float
	 */
	public static function PERCENTILE() {
		$aArgs = self::flattenArray(func_get_args());

		// Calculate
		$entry = array_pop($aArgs);

		if ((is_numeric($entry)) && (!is_string($entry))) {
			if (($entry < 0) || ($entry > 1)) {
				return self::$_errorCodes['num'];
			}
			$mArgs = array();
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					$mArgs[] = $arg;
				}
			}
			$mValueCount = count($mArgs);
			if ($mValueCount > 0) {
				sort($mArgs);
				$count = self::COUNT($mArgs);
				$index = $entry * ($count-1);
				$iBase = floor($index);
				if ($index == $iBase) {
					return $mArgs[$index];
				} else {
					$iNext = $iBase + 1;
					$iProportion = $index - $iBase;
					return $mArgs[$iBase] + (($mArgs[$iNext] - $mArgs[$iBase]) * $iProportion) ;
				}
			}
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * QUARTILE
	 *
	 * Returns the quartile of a data set.
	 *
	 * @param	array of mixed		Data Series
	 * @param	float	$entry		Entry in the series to return
	 * @return	float
	 */
	public static function QUARTILE() {
		$aArgs = self::flattenArray(func_get_args());

		// Calculate
		$entry = floor(array_pop($aArgs));

		if ((is_numeric($entry)) && (!is_string($entry))) {
			$entry /= 4;
			if (($entry < 0) || ($entry > 1)) {
				return self::$_errorCodes['num'];
			}
			return self::PERCENTILE($aArgs,$entry);
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * COUNT
	 *
	 * Counts the number of cells that contain numbers within the list of arguments
	 *
	 * @param	array of mixed		Data Series
	 * @return  int
	 */
	public static function COUNT() {
		// Return value
		$returnValue = 0;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			if ((is_bool($arg)) && (self::$compatibilityMode == self::COMPATIBILITY_OPENOFFICE)) {
				$arg = (int) $arg;
			}
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				++$returnValue;
			}
		}

		// Return
		return $returnValue;
	}

	/**
	 * COUNTBLANK
	 *
	 * Counts the number of empty cells within the list of arguments
	 *
	 * @param	array of mixed		Data Series
	 * @return  int
	 */
	public static function COUNTBLANK() {
		// Return value
		$returnValue = 0;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a blank cell?
			if ((is_null($arg)) || ((is_string($arg)) && ($arg == ''))) {
				++$returnValue;
			}
		}

		// Return
		return $returnValue;
	}

	/**
	 * COUNTA
	 *
	 * Counts the number of cells that are not empty within the list of arguments
	 *
	 * @param	array of mixed		Data Series
	 * @return  int
	 */
	public static function COUNTA() {
		// Return value
		$returnValue = 0;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric, boolean or string value?
			if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) && ($arg != '')))) {
				++$returnValue;
			}
		}

		// Return
		return $returnValue;
	}

	/**
	 * AVERAGE
	 *
	 * Returns the average (arithmetic mean) of the arguments
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function AVERAGE() {
		// Return value
		$returnValue = 0;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$aCount = 0;
		foreach ($aArgs as $arg) {
			if ((is_bool($arg))  && (self::$compatibilityMode == self::COMPATIBILITY_OPENOFFICE)) {
				$arg = (integer) $arg;
			}
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				if (is_null($returnValue)) {
					$returnValue = $arg;
				} else {
					$returnValue += $arg;
				}
				++$aCount;
			}
		}

		// Return
		if ($aCount > 0) {
			return $returnValue / $aCount;
		} else {
			return self::$_errorCodes['divisionbyzero'];
		}
	}

	/**
	 * AVERAGEA
	 *
	 * Returns the average of its arguments, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function AVERAGEA() {
		// Return value
		$returnValue = null;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$aCount = 0;
		foreach ($aArgs as $arg) {
			if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) && ($arg != '')))) {
				if (is_bool($arg)) {
					$arg = (integer) $arg;
				} elseif (is_string($arg)) {
					$arg = 0;
				}
				if (is_null($returnValue)) {
					$returnValue = $arg;
				} else {
					$returnValue += $arg;
				}
				++$aCount;
			}
		}

		// Return
		if ($aCount > 0) {
			return $returnValue / $aCount;
		} else {
			return self::$_errorCodes['divisionbyzero'];
		}
	}

	/**
	 * MEDIAN
	 *
	 * Returns the median of the given numbers. The median is the number in the middle of a set of numbers.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MEDIAN() {
		// Return value
		$returnValue = self::$_errorCodes['num'];

		$mArgs = array();
		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				$mArgs[] = $arg;
			}
		}

		$mValueCount = count($mArgs);
		if ($mValueCount > 0) {
			sort($mArgs,SORT_NUMERIC);
			$mValueCount = $mValueCount / 2;
			if ($mValueCount == floor($mValueCount)) {
				$returnValue = ($mArgs[$mValueCount--] + $mArgs[$mValueCount]) / 2;
			} else {
				$mValueCount == floor($mValueCount);
				$returnValue = $mArgs[$mValueCount];
			}
		}

		// Return
		return $returnValue;
	}

	//
	//	Special variant of array_count_values that isn't limited to strings and integers,
	//		but can work with floating point numbers as values
	//
	private static function modeCalc($data) {
		$frequencyArray = array();
		foreach($data as $datum) {
			$found = False;
			foreach($frequencyArray as $key => $value) {
				if ((string)$value['value'] == (string)$datum) {
					++$frequencyArray[$key]['frequency'];
					$found = True;
					break;
				}
			}
			if (!$found) {
				$frequencyArray[] = array('value'		=> $datum,
										  'frequency'	=>	1 );
			}
		}

		foreach($frequencyArray as $key => $value) {
			$frequencyList[$key] = $value['frequency'];
			$valueList[$key] = $value['value'];
		}
		array_multisort($frequencyList, SORT_DESC, $valueList, SORT_ASC, SORT_NUMERIC, $frequencyArray);

		if ($frequencyArray[0]['frequency'] == 1) {
			return self::NA();
		}
		return $frequencyArray[0]['value'];
	}

	/**
	 * MODE
	 *
	 * Returns the most frequently occurring, or repetitive, value in an array or range of data
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MODE() {
		// Return value
		$returnValue = self::NA();

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());

		$mArgs = array();
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				$mArgs[] = $arg;
			}
		}

		if (count($mArgs) > 0) {
			return self::modeCalc($mArgs);
		}

		// Return
		return $returnValue;
	}

	/**
	 * DEVSQ
	 *
	 * Returns the sum of squares of deviations of data points from their sample mean.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function DEVSQ() {
		// Return value
		$returnValue = null;

		$aMean = self::AVERAGE(func_get_args());
		if (!is_null($aMean)) {
			$aArgs = self::flattenArray(func_get_args());

			$aCount = -1;
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_bool($arg))  && (self::$compatibilityMode == self::COMPATIBILITY_OPENOFFICE)) {
					$arg = (int) $arg;
				}
				if ((is_numeric($arg)) && (!is_string($arg))) {
					if (is_null($returnValue)) {
						$returnValue = pow(($arg - $aMean),2);
					} else {
						$returnValue += pow(($arg - $aMean),2);
					}
					++$aCount;
				}
			}

			// Return
			if (is_null($returnValue)) {
				return self::$_errorCodes['num'];
			} else {
				return $returnValue;
			}
		}
		return self::NA();
	}

	/**
	 * AVEDEV
	 *
	 * Returns the average of the absolute deviations of data points from their mean.
	 * AVEDEV is a measure of the variability in a data set.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function AVEDEV() {
		$aArgs = self::flattenArray(func_get_args());

		// Return value
		$returnValue = null;

		$aMean = self::AVERAGE($aArgs);
		if ($aMean != self::$_errorCodes['divisionbyzero']) {
			$aCount = 0;
			foreach ($aArgs as $arg) {
				if ((is_bool($arg))  && (self::$compatibilityMode == self::COMPATIBILITY_OPENOFFICE)) {
					$arg = (integer) $arg;
				}
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					if (is_null($returnValue)) {
						$returnValue = abs($arg - $aMean);
					} else {
						$returnValue += abs($arg - $aMean);
					}
					++$aCount;
				}
			}

			// Return
			return $returnValue / $aCount ;
		}
		return self::$_errorCodes['num'];
	}

	/**
	 * GEOMEAN
	 *
	 * Returns the geometric mean of an array or range of positive data. For example, you
	 * can use GEOMEAN to calculate average growth rate given compound interest with
	 * variable rates.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function GEOMEAN() {
		$aMean = self::PRODUCT(func_get_args());
		if (is_numeric($aMean) && ($aMean > 0)) {
			$aArgs = self::flattenArray(func_get_args());
			$aCount = self::COUNT($aArgs) ;
			if (self::MIN($aArgs) > 0) {
				return pow($aMean, (1 / $aCount));
			}
		}
		return self::$_errorCodes['num'];
	}

	/**
	 * HARMEAN
	 *
	 * Returns the harmonic mean of a data set. The harmonic mean is the reciprocal of the
	 * arithmetic mean of reciprocals.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function HARMEAN() {
		// Return value
		$returnValue = self::NA();

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		if (self::MIN($aArgs) < 0) {
			return self::$_errorCodes['num'];
		}
		$aCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				if ($arg <= 0) {
					return self::$_errorCodes['num'];
				}
				if (is_null($returnValue)) {
					$returnValue = (1 / $arg);
				} else {
					$returnValue += (1 / $arg);
				}
				++$aCount;
			}
		}

		// Return
		if ($aCount > 0) {
			return 1 / ($returnValue / $aCount);
		} else {
			return $returnValue;
		}
	}

	/**
	 * TRIMMEAN
	 *
	 * Returns the mean of the interior of a data set. TRIMMEAN calculates the mean
	 * taken by excluding a percentage of data points from the top and bottom tails
	 * of a data set.
	 *
	 * @param	array of mixed		Data Series
	 * @param	float	Percentage to discard
	 * @return	float
	 */
	public static function TRIMMEAN() {
		$aArgs = self::flattenArray(func_get_args());

		// Calculate
		$percent = array_pop($aArgs);

		if ((is_numeric($percent)) && (!is_string($percent))) {
			if (($percent < 0) || ($percent > 1)) {
				return self::$_errorCodes['num'];
			}
			$mArgs = array();
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					$mArgs[] = $arg;
				}
			}
			$discard = floor(self::COUNT($mArgs) * $percent / 2);
			sort($mArgs);
			for ($i=0; $i < $discard; ++$i) {
				array_pop($mArgs);
				array_shift($mArgs);
			}
			return self::AVERAGE($mArgs);
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * STDEV
	 *
	 * Estimates standard deviation based on a sample. The standard deviation is a measure of how
	 * widely values are dispersed from the average value (the mean).
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function STDEV() {
		// Return value
		$returnValue = null;

		$aMean = self::AVERAGE(func_get_args());
		if (!is_null($aMean)) {
			$aArgs = self::flattenArray(func_get_args());

			$aCount = -1;
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					if (is_null($returnValue)) {
						$returnValue = pow(($arg - $aMean),2);
					} else {
						$returnValue += pow(($arg - $aMean),2);
					}
					++$aCount;
				}
			}

			// Return
			if (($aCount > 0) && ($returnValue > 0)) {
				return sqrt($returnValue / $aCount);
			}
		}
		return self::$_errorCodes['divisionbyzero'];
	}

	/**
	 * STDEVA
	 *
	 * Estimates standard deviation based on a sample, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function STDEVA() {
		// Return value
		$returnValue = null;

		$aMean = self::AVERAGEA(func_get_args());
		if (!is_null($aMean)) {
			$aArgs = self::flattenArray(func_get_args());

			$aCount = -1;
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) & ($arg != '')))) {
					if (is_bool($arg)) {
						$arg = (integer) $arg;
					} elseif (is_string($arg)) {
						$arg = 0;
					}
					if (is_null($returnValue)) {
						$returnValue = pow(($arg - $aMean),2);
					} else {
						$returnValue += pow(($arg - $aMean),2);
					}
					++$aCount;
				}
			}

			// Return
			if (($aCount > 0) && ($returnValue > 0)) {
				return sqrt($returnValue / $aCount);
			}
		}
		return self::$_errorCodes['divisionbyzero'];
	}

	/**
	 * STDEVP
	 *
	 * Calculates standard deviation based on the entire population
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function STDEVP() {
		// Return value
		$returnValue = null;

		$aMean = self::AVERAGE(func_get_args());
		if (!is_null($aMean)) {
			$aArgs = self::flattenArray(func_get_args());

			$aCount = 0;
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					if (is_null($returnValue)) {
						$returnValue = pow(($arg - $aMean),2);
					} else {
						$returnValue += pow(($arg - $aMean),2);
					}
					++$aCount;
				}
			}

			// Return
			if (($aCount > 0) && ($returnValue > 0)) {
				return sqrt($returnValue / $aCount);
			}
		}
		return self::$_errorCodes['divisionbyzero'];
	}

	/**
	 * STDEVPA
	 *
	 * Calculates standard deviation based on the entire population, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function STDEVPA() {
		// Return value
		$returnValue = null;

		$aMean = self::AVERAGEA(func_get_args());
		if (!is_null($aMean)) {
			$aArgs = self::flattenArray(func_get_args());

			$aCount = 0;
			foreach ($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) & ($arg != '')))) {
					if (is_bool($arg)) {
						$arg = (integer) $arg;
					} elseif (is_string($arg)) {
						$arg = 0;
					}
					if (is_null($returnValue)) {
						$returnValue = pow(($arg - $aMean),2);
					} else {
						$returnValue += pow(($arg - $aMean),2);
					}
					++$aCount;
				}
			}

			// Return
			if (($aCount > 0) && ($returnValue > 0)) {
				return sqrt($returnValue / $aCount);
			}
		}
		return self::$_errorCodes['divisionbyzero'];
	}

	/**
	 * VARFunc
	 *
	 * Estimates variance based on a sample.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function VARFunc() {
		// Return value
		$returnValue = self::$_errorCodes['divisionbyzero'];

		$summerA = $summerB = 0;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$aCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				$summerA += ($arg * $arg);
				$summerB += $arg;
				++$aCount;
			}
		}

		// Return
		if ($aCount > 1) {
			$summerA = $summerA * $aCount;
			$summerB = ($summerB * $summerB);
			$returnValue = ($summerA - $summerB) / ($aCount * ($aCount - 1));
		}
		return $returnValue;
	}

	/**
	 * VARA
	 *
	 * Estimates variance based on a sample, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function VARA() {
		// Return value
		$returnValue = self::$_errorCodes['divisionbyzero'];

		$summerA = $summerB = 0;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$aCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
				if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) & ($arg != '')))) {
				if (is_bool($arg)) {
					$arg = (integer) $arg;
				} elseif (is_string($arg)) {
					$arg = 0;
				}
				$summerA += ($arg * $arg);
				$summerB += $arg;
				++$aCount;
			}
		}

		// Return
		if ($aCount > 1) {
			$summerA = $summerA * $aCount;
			$summerB = ($summerB * $summerB);
			$returnValue = ($summerA - $summerB) / ($aCount * ($aCount - 1));
		}
		return $returnValue;
	}

	/**
	 * VARP
	 *
	 * Calculates variance based on the entire population
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function VARP() {
		// Return value
		$returnValue = self::$_errorCodes['divisionbyzero'];

		$summerA = $summerB = 0;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$aCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) && (!is_string($arg))) {
				$summerA += ($arg * $arg);
				$summerB += $arg;
				++$aCount;
			}
		}

		// Return
		if ($aCount > 0) {
			$summerA = $summerA * $aCount;
			$summerB = ($summerB * $summerB);
			$returnValue = ($summerA - $summerB) / ($aCount * $aCount);
		}
		return $returnValue;
	}

	/**
	 * VARPA
	 *
	 * Calculates variance based on the entire population, including numbers, text, and logical values
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function VARPA() {
		// Return value
		$returnValue = self::$_errorCodes['divisionbyzero'];

		$summerA = $summerB = 0;

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$aCount = 0;
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if ((is_numeric($arg)) || (is_bool($arg)) || ((is_string($arg) & ($arg != '')))) {
				if (is_bool($arg)) {
					$arg = (integer) $arg;
				} elseif (is_string($arg)) {
					$arg = 0;
				}
				$summerA += ($arg * $arg);
				$summerB += $arg;
				++$aCount;
			}
		}

		// Return
		if ($aCount > 0) {
			$summerA = $summerA * $aCount;
			$summerB = ($summerB * $summerB);
			$returnValue = ($summerA - $summerB) / ($aCount * $aCount);
		}
		return $returnValue;
	}

	/**
	 * SUBTOTAL
	 *
	 * Returns a subtotal in a list or database.
	 *
	 * @param	int		the number 1 to 11 that specifies which function to
	 *					use in calculating subtotals within a list.
	 * @param	array of mixed		Data Series
	 * @return	float
	 */
	public static function SUBTOTAL() {
		$aArgs = self::flattenArray(func_get_args());

		// Calculate
		$subtotal = array_shift($aArgs);

		if ((is_numeric($subtotal)) && (!is_string($subtotal))) {
			switch($subtotal) {
				case 1	:
					return self::AVERAGE($aArgs);
					break;
				case 2	:
					return self::COUNT($aArgs);
					break;
				case 3	:
					return self::COUNTA($aArgs);
					break;
				case 4	:
					return self::MAX($aArgs);
					break;
				case 5	:
					return self::MIN($aArgs);
					break;
				case 6	:
					return self::PRODUCT($aArgs);
					break;
				case 7	:
					return self::STDEV($aArgs);
					break;
				case 8	:
					return self::STDEVP($aArgs);
					break;
				case 9	:
					return self::SUM($aArgs);
					break;
				case 10	:
					return self::VARFunc($aArgs);
					break;
				case 11	:
					return self::VARP($aArgs);
					break;
			}
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * SQRTPI
	 *
	 * Returns the square root of (number * pi).
	 *
	 * @param	float	$number		Number
	 * @return  float	Square Root of Number * Pi
	 */
	public static function SQRTPI($number) {
		$number	= self::flattenSingleValue($number);

		if (is_numeric($number)) {
			if ($number < 0) {
				return self::$_errorCodes['num'];
			}
			return sqrt($number * pi()) ;
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * FACT
	 *
	 * Returns the factorial of a number.
	 *
	 * @param	float	$factVal	Factorial Value
	 * @return  int		Factorial
	 */
	public static function FACT($factVal) {
		$factVal	= self::flattenSingleValue($factVal);

		if (is_numeric($factVal)) {
			if ($factVal < 0) {
				return self::$_errorCodes['num'];
			}
			$factLoop = floor($factVal);
			if (self::$compatibilityMode == self::COMPATIBILITY_GNUMERIC) {
				if ($factVal > $factLoop) {
					return self::$_errorCodes['num'];
				}
			}
			$factorial = 1;
			while ($factLoop > 1) {
				$factorial *= $factLoop--;
			}
			return $factorial ;
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * FACTDOUBLE
	 *
	 * Returns the double factorial of a number.
	 *
	 * @param	float	$factVal	Factorial Value
	 * @return  int		Double Factorial
	 */
	public static function FACTDOUBLE($factVal) {
		$factLoop	= floor(self::flattenSingleValue($factVal));

		if (is_numeric($factLoop)) {
			if ($factVal < 0) {
				return self::$_errorCodes['num'];
			}
			$factorial = 1;
			while ($factLoop > 1) {
				$factorial *= $factLoop--;
				--$factLoop;
			}
			return $factorial ;
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * MULTINOMIAL
	 *
	 * Returns the ratio of the factorial of a sum of values to the product of factorials.
	 *
	 * @param	array of mixed		Data Series
	 * @return  float
	 */
	public static function MULTINOMIAL() {

		// Loop through arguments
		$aArgs = self::flattenArray(func_get_args());
		$summer = 0;
		$divisor = 1;
		foreach ($aArgs as $arg) {
			// Is it a numeric value?
			if (is_numeric($arg)) {
				if ($arg < 1) {
					return self::$_errorCodes['num'];
				}
				$summer += floor($arg);
				$divisor *= self::FACT($arg);
			} else {
				return self::$_errorCodes['value'];
			}
		}

		// Return
		if ($summer > 0) {
			$summer = self::FACT($summer);
			return $summer / $divisor;
		}
		return 0;
	}

	/**
	 * CEILING
	 *
	 * Returns number rounded up, away from zero, to the nearest multiple of significance.
	 *
	 * @param	float	$number			Number to round
	 * @param	float	$significance	Significance
	 * @return  float	Rounded Number
	 */
	public static function CEILING($number,$significance=null) {
		$number			= self::flattenSingleValue($number);
		$significance	= self::flattenSingleValue($significance);

		if ((is_null($significance)) && (self::$compatibilityMode == self::COMPATIBILITY_GNUMERIC)) {
			$significance = $number/abs($number);
		}

		if ((is_numeric($number)) && (is_numeric($significance))) {
			if (self::SIGN($number) == self::SIGN($significance)) {
				if ($significance == 0.0) {
					return 0;
				}
				return ceil($number / $significance) * $significance;
			} else {
				return self::$_errorCodes['num'];
			}
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * EVEN
	 *
	 * Returns number rounded up to the nearest even integer.
	 *
	 * @param	float	$number			Number to round
	 * @return  int		Rounded Number
	 */
	public static function EVEN($number) {
		$number	= self::flattenSingleValue($number);

		if (is_numeric($number)) {
			$significance = 2 * self::SIGN($number);
			return self::CEILING($number,$significance);
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * ODD
	 *
	 * Returns number rounded up to the nearest odd integer.
	 *
	 * @param	float	$number			Number to round
	 * @return  int		Rounded Number
	 */
	public static function ODD($number) {
		$number	= self::flattenSingleValue($number);

		if (is_numeric($number)) {
			$significance = self::SIGN($number);
			if ($significance == 0) {
				return 1;
			}
			$result = self::CEILING($number,$significance);
			if (self::IS_EVEN($result)) {
				$result += $significance;
			}
			return $result;
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * ROUNDUP
	 *
	 * Rounds a number up to a specified number of decimal places
	 *
	 * @param	float	$number			Number to round
	 * @param	int		$digits			Number of digits to which you want to round $number
	 * @return  float	Rounded Number
	 */
	public static function ROUNDUP($number,$digits) {
		$number	= self::flattenSingleValue($number);
		$digits	= self::flattenSingleValue($digits);

		if (is_numeric($number)) {
			if ((is_numeric($digits)) && ($digits >= 0)) {
				$significance = pow(10,$digits);
				return ceil($number * $significance) / $significance;
			}
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * ROUNDDOWN
	 *
	 * Rounds a number down to a specified number of decimal places
	 *
	 * @param	float	$number			Number to round
	 * @param	int		$digits			Number of digits to which you want to round $number
	 * @return  float	Rounded Number
	 */
	public static function ROUNDDOWN($number,$digits) {
		$number	= self::flattenSingleValue($number);
		$digits	= self::flattenSingleValue($digits);

		if (is_numeric($number)) {
			if ((is_numeric($digits)) && ($digits >= 0)) {
				$significance = pow(10,$digits);
				return floor($number * $significance) / $significance;
			}
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * MROUND
	 *
	 * Rounds a number to the nearest multiple of a specified value
	 *
	 * @param	float	$number			Number to round
	 * @param	int		$multiple		Multiple to which you want to round $number
	 * @return  float	Rounded Number
	 */
	public static function MROUND($number,$multiple) {
		$number		= self::flattenSingleValue($number);
		$multiple	= self::flattenSingleValue($multiple);

		if ((is_numeric($number)) && (is_numeric($multiple))) {
			if ((self::SIGN($number)) == (self::SIGN($multiple))) {
				$lowerVal = floor($number / $multiple) * $multiple;
				$upperVal = ceil($number / $multiple) * $multiple;
				$adjustUp = abs($number - $upperVal);
				$adjustDown = abs($number - $lowerVal) + PRECISION;
				if ($adjustDown < $adjustUp) {
					return $lowerVal;
				}
				return $upperVal;
			}
			return self::$_errorCodes['num'];
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * SIGN
	 *
	 * Determines the sign of a number. Returns 1 if the number is positive, zero (0)
	 * if the number is 0, and -1 if the number is negative.
	 *
	 * @param	float	$number			Number to round
	 * @return  int		sign value
	 */
	public static function SIGN($number) {
		$number	= self::flattenSingleValue($number);

		if (is_numeric($number)) {
			if ($number == 0.0) {
				return 0;
			}
			return $number / abs($number);
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * FLOOR
	 *
	 * Rounds number down, toward zero, to the nearest multiple of significance.
	 *
	 * @param	float	$number			Number to round
	 * @param	float	$significance	Significance
	 * @return  float	Rounded Number
	 */
	public static function FLOOR($number,$significance=null) {
		$number			= self::flattenSingleValue($number);
		$significance	= self::flattenSingleValue($significance);

		if ((is_null($significance)) && (self::$compatibilityMode == self::COMPATIBILITY_GNUMERIC)) {
			$significance = $number/abs($number);
		}

		if ((is_numeric($number)) && (is_numeric($significance))) {
			if ((float) $significance == 0.0) {
				return self::$_errorCodes['divisionbyzero'];
			}
			if (self::SIGN($number) == self::SIGN($significance)) {
				return floor($number / $significance) * $significance;
			} else {
				return self::$_errorCodes['num'];
			}
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * PERMUT
	 *
	 * Returns the number of permutations for a given number of objects that can be
	 * selected from number objects. A permutation is any set or subset of objects or
	 * events where internal order is significant. Permutations are different from
	 * combinations, for which the internal order is not significant. Use this function
	 * for lottery-style probability calculations.
	 *
	 * @param	int		$numObjs	Number of different objects
	 * @param	int		$numInSet	Number of objects in each permutation
	 * @return  int		Number of permutations
	 */
	public static function PERMUT($numObjs,$numInSet) {
		$numObjs	= self::flattenSingleValue($numObjs);
		$numInSet	= self::flattenSingleValue($numInSet);

		if ((is_numeric($numObjs)) && (is_numeric($numInSet))) {
			if ($numObjs < $numInSet) {
				return self::$_errorCodes['num'];
			}
			return self::FACT($numObjs) / self::FACT($numObjs - $numInSet);
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * COMBIN
	 *
	 * Returns the number of combinations for a given number of items. Use COMBIN to
	 * determine the total possible number of groups for a given number of items.
	 *
	 * @param	int		$numObjs	Number of different objects
	 * @param	int		$numInSet	Number of objects in each combination
	 * @return  int		Number of combinations
	 */
	public static function COMBIN($numObjs,$numInSet) {
		$numObjs	= self::flattenSingleValue($numObjs);
		$numInSet	= self::flattenSingleValue($numInSet);

		if ((is_numeric($numObjs)) && (is_numeric($numInSet))) {
			if ($numObjs < $numInSet) {
				return self::$_errorCodes['num'];
			} elseif ($numInSet < 0) {
				return self::$_errorCodes['num'];
			}
			return (self::FACT($numObjs) / self::FACT($numObjs - $numInSet)) / self::FACT($numInSet);
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * SERIESSUM
	 *
	 * Returns the sum of a power series
	 *
	 * @param	float			$x	Input value to the power series
	 * @param	float			$n	Initial power to which you want to raise $x
	 * @param	float			$m	Step by which to increase $n for each term in the series
	 * @param	array of mixed		Data Series
	 * @return	float
	 */
	public static function SERIESSUM() {
		// Return value
		$returnValue = 0;

		// Loop trough arguments
		$aArgs = self::flattenArray(func_get_args());

		$x = array_shift($aArgs);
		$n = array_shift($aArgs);
		$m = array_shift($aArgs);

		if ((is_numeric($x)) && (is_numeric($n)) && (is_numeric($m))) {
			// Calculate
			$i = 0;
			foreach($aArgs as $arg) {
				// Is it a numeric value?
				if ((is_numeric($arg)) && (!is_string($arg))) {
					$returnValue += $arg * pow($x,$n + ($m * $i++));
				} else {
					return self::$_errorCodes['value'];
				}
			}
			// Return
			return $returnValue;
		}
		return self::$_errorCodes['value'];
	}

	/**
	 * STANDARDIZE
	 *
	 * Returns a normalized value from a distribution characterized by mean and standard_dev.
	 *
	 * @param	float	$value		Value to normalize
	 * @param	float	$mean		Mean Value
	 * @param	float	$stdDev		Standard Deviation
	 * @return  float	Standardized value
	 */
	public static function STANDARDIZE($value,$mean,$stdDev) {
		$value	= self::flattenSingleValue($value);
		$mean	= self::flattenSingleValue($mean);
		$stdDev	= self::flattenSingleValue($stdDev);

		if ((is_numeric($value)) && (is_numeric($mean)) && (is_numeric($stdDev))) {
			if ($stdDev <= 0) {
				return self::$_errorCodes['num'];
			}
			return ($value - $mean) / $stdDev ;
		}
		return self::$_errorCodes['value'];
	}

	//
	//	Private method to return an array of the factors of the input value
	//
	private static function factors($value) {
		$startVal = floor(sqrt($value));

		$factorArray = array();
		for ($i = $startVal; $i > 1; --$i) {
			if (($value % $i) == 0) {
				$factorArray = array_merge($factorArray,self::factors($value / $i));
				$factorArray = array_merge($factorArray,self::factors($i));
				if ($i <= sqrt($value)) {
					break;
				}
			}
		}
		if (count($factorArray) > 0) {
			rsort($factorArray);
			return $factorArray;
		} else {
			return array((integer) $value);
		}
	}

	/**
	 * LCM
	 *
	 * Returns the lowest common multiplier of a series of numbers
	 *
	 * @param	$array	Values to calculate the Lowest Common Multiplier
	 * @return  int		Lowest Common Multiplier
	 */
	public static function LCM() {
		$aArgs = self::flattenArray(func_get_args());

		$returnValue = 1;
		$allPoweredFactors = array();
		foreach($aArgs as $value) {
			if (!is_numeric($value)) {
				return self::$_errorCodes['value'];
			}
			if ($value < 1) {
				return self::$_errorCodes['num'];
			}
			$myFactors = self::factors(floor($value));
			$myCountedFactors = array_count_values($myFactors);
			$myPoweredFactors = array();
			foreach($myCountedFactors as $myCountedFactor => $myCountedPower) {
				$myPoweredFactors[$myCountedFactor] = pow($myCountedFactor,$myCountedPower);
			}
			foreach($myPoweredFactors as $myPoweredValue => $myPoweredFactor) {
				if (array_key_exists($myPoweredValue,$allPoweredFactors)) {
					if ($allPoweredFactors[$myPoweredValue] < $myPoweredFactor) {
						$allPoweredFactors[$myPoweredValue] = $myPoweredFactor;
					}
				} else {
					$allPoweredFactors[$myPoweredValue] = $myPoweredFactor;
				}
			}
		}
		foreach($allPoweredFactors as $allPoweredFactor) {
			$returnValue *= (integer) $allPoweredFactor;
		}
		return $returnValue;
	}

	/**
	 * GCD
	 *
	 * Returns the greatest common divisor of a series of numbers
	 *
	 * @param	$array	Values to calculate the Greatest Common Divisor
	 * @return  int		Greatest Common Divisor
	 */
	public static function GCD() {
		$aArgs = self::flattenArray(func_get_args());

		$returnValue = 1;
		$allPoweredFactors = array();
		foreach($aArgs as $value) {
			if ($value == 0) {
				return 0;
			}
			$myFactors = self::factors($value);
			$myCountedFactors = array_count_values($myFactors);
			$allValuesFactors[] = $myCountedFactors;
		}
		$allValuesCount = count($allValuesFactors);
		$mergedArray = $allValuesFactors[0];
		for ($i=1;$i < $allValuesCount; ++$i) {
			$mergedArray = array_intersect_key($mergedArray,$allValuesFactors[$i]);
		}
		$mergedArrayValues = count($mergedArray);
		if ($mergedArrayValues == 0) {
			return $returnValue;
		} elseif ($mergedArrayValues > 1) {
			foreach($mergedArray as $mergedKey => $mergedValue) {
				foreach($allValuesFactors as $highestPowerTest) {
					foreach($highestPowerTest as $testKey => $testValue) {
						if (($testKey == $mergedKey) && ($testValue < $mergedValue)) {
							$mergedArray[$mergedKey] = $testValue;
							$mergedValue = $testValue;
						}
					}
				}
			}

			$returnValue = 1;
			foreach($mergedArray as $key => $value) {
				$returnValue *= pow($key,$value);
			}
			return $returnValue;
		} else {
			$keys = array_keys($mergedArray);
			$key = $keys[0];
			$value = $mergedArray[$key];
			foreach($allValuesFactors as $testValue) {
				foreach($testValue as $mergedKey => $mergedValue) {
					if (($mergedKey == $key) && ($mergedValue < $value)) {
						$value = $mergedValue;
					}
				}
			}
			return pow($key,$value);
		}
	}

	/**
	 * BINOMDIST
	 *
	 * Returns the individual term binomial distribution probability. Use BINOMDIST in problems with
	 * a fixed number of tests or trials, when the outcomes of any trial are only success or failure,
	 * when trials are independent, and when the probability of success is constant throughout the
	 * experiment. For example, BINOMDIST can calculate the probability that two of the next three
	 * ba…