Polynomial regression in ruby

polynomial_regression.rb

require 'matrix'

def polynomial_regression x, y, degree
  rows = x.map do |i|
    (0..degree).map { |power| (i ** power).to_f }
  end
  mx, my = Matrix.rows(rows), Matrix.columns([y])
  ((mx.transpose * mx).inv * mx.transpose * my).transpose.row(0).to_a.reverse
end