protected function directSumMatrix(Matrix $value)
    {
        $originalColumnCount = count($this->matrix[0]);
        $originalRowCount = count($this->matrix);
        $additionalColumnCount = $value->columns;
        $additionalRowCount = $value->rows;
        $value = $value->toArray();

        for ($row = 0; $row < $this->rows; ++$row) {
            $this->matrix[$row] = array_merge($this->matrix[$row], array_fill(0, $additionalColumnCount, 0));
        }

        $this->matrix = array_merge(
            $this->matrix,
            array_fill(0, $additionalRowCount, array_fill(0, $originalColumnCount, 0))
        );

        for ($row = $originalRowCount; $row < $originalRowCount + $additionalRowCount; ++$row) {
            array_splice(
                $this->matrix[$row],
                $originalColumnCount,
                $additionalColumnCount,
                $value[$row - $originalRowCount]
            );
        }

        return $this;
    }