MathPHP\Functions\Piecewise::__construct PHP Метод

    public function __construct(array $intervals, array $functions)
    {
        if (count($intervals) !== count($functions)) {
            throw new Exception\BadDataException("For a piecewise function you must provide the same number of intervals as functions.");
        }
        if (count(array_filter($functions, "is_callable")) !== count($intervals)) {
            throw new Exception\BadDataException("Not every function provided is valid. Ensure that each function is callable.");
        }
        $unsortedIntervals = $intervals;
        // Sort intervals such that start of intervals is increasing
        usort($intervals, function ($a, $b) {
            return $a[0] <=> $b[0];
        });
        foreach ($intervals as $interval) {
            // Store values from previous interval
            $lastA = $a ?? -INF;
            $lastB = $b ?? -INF;
            $lastBOpen = $bOpen ?? false;
            if (count(array_filter($interval, "is_numeric")) !== 2) {
                throw new Exception\BadDataException("Each interval must contain two numbers.");
            }
            // Fetch values from current interval
            $a = $interval[0];
            $b = $interval[1];
            $aOpen = $interval[2] ?? false;
            $bOpen = $interval[3] ?? false;
            if ($a === $b and ($aOpen or $bOpen)) {
                throw new Exception\BadDataException("Your interval [{$a}, {$b}] is a point and thus needs to be closed at both ends");
            }
            if ($a > $b) {
                throw new Exception\BadDataException("Interval must be increasing. Try again using [{$b}, {$a}] instead of [{$a}, {$b}]");
            }
            if ($a === $lastB and !$aOpen and !$lastBOpen) {
                throw new Exception\BadDataException("The intervals [{$lastA}, {$lastB}] and [{$a}, {$b}] share a point, but both intervals are also closed at that point. For intervals to share a point, one or both sides of that point must be open.");
            }
            if ($a < $lastB) {
                throw new Exception\BadDataException("The intervals [{$lastA}, {$lastB}] and [{$a}, {$b}] overlap. The subintervals of a piecewise functions cannot overlap.");
            }
        }
        $this->intervals = $unsortedIntervals;
        $this->functions = $functions;
    }