MathPHP\Functions\Map\Single::sqrt PHP Метод

    public static function sqrt(array $xs) : array
    {
        return array_map(function ($x) {
            return sqrt($x);
        }, $xs);
    }

 /**
  * Standard error of the regression parameters (coefficients)
  *
  *              _________
  *             /  ∑eᵢ²
  *            /  -----
  * se(m) =   /     ν
  *          /  ---------
  *         √   ∑⟮xᵢ - μ⟯²
  *
  *  where
  *    eᵢ = residual (difference between observed value and value predicted by the model)
  *    ν  = n - 2  degrees of freedom
  *
  *           ______
  *          / ∑xᵢ²
  * se(b) = /  ----
  *        √    n
  *
  * @return array [m => se(m), b => se(b)]
  */
 public function standardErrors()
 {
     $X = new VandermondeMatrix($this->xs, 2);
     $⟮XᵀX⟯⁻¹ = $this->⟮XᵀX⟯⁻¹;
     $σ² = $this->meanSquareResidual();
     $standard_error_matrix = $⟮XᵀX⟯⁻¹->scalarMultiply($σ²);
     $standard_error_array = Single::sqrt($standard_error_matrix->getDiagonalElements());
     return ['m' => $standard_error_array[1], 'b' => $standard_error_array[0]];
 }