MathPHP\LinearAlgebra\Matrix::frobeniusNorm PHP Method

    public function frobeniusNorm()
    {
        $m = $this->m;
        $n = $this->n;
        $ΣΣaᵢⱼ² = 0;
        for ($i = 0; $i < $m; $i++) {
            for ($j = 0; $j < $n; $j++) {
                $ΣΣaᵢⱼ² += $this->A[$i][$j] ** 2;
            }
        }
        return sqrt($ΣΣaᵢⱼ²);
    }