MathPHP\LinearAlgebra\Matrix::directSum PHP Method

    public function directSum(Matrix $B) : Matrix
    {
        $m = $this->m + $B->getM();
        $n = $this->n + $B->getN();
        $R = [];
        for ($i = 0; $i < $m; $i++) {
            for ($j = 0; $j < $n; $j++) {
                $R[$i][$j] = 0;
            }
        }
        for ($i = 0; $i < $this->m; $i++) {
            for ($j = 0; $j < $this->n; $j++) {
                $R[$i][$j] = $this->A[$i][$j];
            }
        }
        $m = $B->getM();
        $n = $B->getN();
        for ($i = 0; $i < $m; $i++) {
            for ($j = 0; $j < $n; $j++) {
                $R[$i + $this->m][$j + $this->n] = $B[$i][$j];
            }
        }
        return MatrixFactory::create($R);
    }