Find saddle points from given matrix

saddle_points.rb

require 'matrix'

matrix = Matrix[
  [9, 2, 8, 6],
  [5, 3, 1, 5],
  [6, 8, 7, 9]
]

cols = matrix.column_vectors
rows = matrix.row_vectors

saddle_points = []
matrix.each_with_index do |point, row, col|
  if (point == rows[row].max) &&
      (point == cols[col].min)
    saddle_points << [row, col]
  end
end

saddle_points