public function oneNorm() { $n = $this->n; $‖A‖₁ = array_sum(Map\Single::abs(array_column($this->A, 0))); for ($j = 1; $j < $n; $j++) { $‖A‖₁ = max($‖A‖₁, array_sum(Map\Single::abs(array_column($this->A, $j)))); } return $‖A‖₁; }