PHPOffice / PhpSpreadsheet

     * @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)

    {

        $yValues = Functions::flattenArray($yValues);

        $xValues = Functions::flattenArray($xValues);

        $newValues = Functions::flattenArray($newValues);

        $const = (is_null($const)) ? true : (boolean) Functions::flattenSingleValue($const);

        $bestFitExponential = \PhpSpreadsheet\Shared\trend\trend::calculate(\PhpSpreadsheet\Shared\trend\trend::TREND_EXPONENTIAL, $yValues, $xValues, $const);

        if (empty($newValues)) {

            $newValues = $bestFitExponential->getXValues();

        }

        $returnArray = array();

        foreach ($newValues as $xValue) {

            $returnArray[0][] = $bestFitExponential->getValueOfYForX($xValue);

        }

        return $returnArray;

    }

    /**

     * @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)

    {

        $yValues = Functions::flattenArray($yValues);

        $xValues = Functions::flattenArray($xValues);

        $newValues = Functions::flattenArray($newValues);

        $const = (is_null($const)) ? true : (boolean) Functions::flattenSingleValue($const);

        $bestFitLinear = \PhpSpreadsheet\Shared\trend\trend::calculate(\PhpSpreadsheet\Shared\trend\trend::TREND_LINEAR, $yValues, $xValues, $const);

        if (empty($newValues)) {

            $newValues = $bestFitLinear->getXValues();

        }

        $returnArray = array();

        foreach ($newValues as $xValue) {

            $returnArray[0][] = $bestFitLinear->getValueOfYForX($xValue);

        }

        return $returnArray;

    }

    /**