/**
* TREND
*
* Returns values along a linear trend
*
* @param array of mixed Data Series Y
* @param array of mixed Data Series X
* @param array of mixed Values of X for which we want to find Y
* @param boolean A logical value specifying whether to force the intersect to equal 0.
* @return array of float
*/
public static function TREND($yValues, $xValues = array(), $newValues = array(), $const = True)
{
$yValues = PHPExcel_Calculation_Functions::flattenArray($yValues);
$xValues = PHPExcel_Calculation_Functions::flattenArray($xValues);
$newValues = PHPExcel_Calculation_Functions::flattenArray($newValues);
$const = is_null($const) ? True : (bool) PHPExcel_Calculation_Functions::flattenSingleValue($const);
$bestFitLinear = trendClass::calculate(trendClass::TREND_LINEAR, $yValues, $xValues, $const);
if (count($newValues) == 0) {
$newValues = $bestFitLinear->getXValues();
}
$returnArray = array();
foreach ($newValues as $xValue) {
$returnArray[0][] = $bestFitLinear->getValueOfYForX($xValue);
}
return $returnArray;
}
/**
* GROWTH
*
* Returns values along a predicted emponential trend
*
* @param array of mixed Data Series Y
* @param array of mixed Data Series X
* @param array of mixed Values of X for which we want to find Y
* @param boolean A logical value specifying whether to force the intersect to equal 0.
* @return array of float
*/
public static function GROWTH($yValues, $xValues = array(), $newValues = array(), $const = True)
{
$yValues = self::flattenArray($yValues);
$xValues = self::flattenArray($xValues);
$newValues = self::flattenArray($newValues);
$const = (bool) self::flattenSingleValue($const);
$bestFitExponential = trendClass::calculate(trendClass::TREND_EXPONENTIAL, $yValues, $xValues, $const);
if (count($newValues) == 0) {
$newValues = $bestFitExponential->getXValues();
}
$returnArray = array();
foreach ($newValues as $xValue) {
$returnArray[0][] = $bestFitExponential->getValueOfYForX($xValue);
}
return $returnArray;
}