MathPHP\Functions\Piecewise::getFunction PHP Метод

    public function getFunction($x)
    {
        foreach ($this->intervals as $i => $interval) {
            $a = $interval[0];
            $b = $interval[1];
            $aOpen = $interval[2] ?? false;
            $bOpen = $interval[3] ?? false;
            // Four permutations: open-open, open-closed, closed-open, closed-closed
            if ($aOpen && $bOpen) {
                if ($x > $a && $x < $b) {
                    return $this->functions[$i];
                }
            } elseif ($aOpen && !$bOpen) {
                if ($x > $a && $x <= $b) {
                    return $this->functions[$i];
                }
            } elseif (!$aOpen && $bOpen) {
                if ($x >= $a && $x < $b) {
                    return $this->functions[$i];
                }
            } elseif (!$aOpen && !$bOpen) {
                if ($x >= $a && $x <= $b) {
                    return $this->functions[$i];
                }
            }
        }
        return false;
    }