require 'matrix'

a = Matrix[
  [3.0, 9.0, 7.0, 5.0],
  [1.0, 1.0, 0.0, 8.0],
  [6.0, 7.0, 0.0, 9.0],
  [8.0, 2.0, 1.0, 1.0],
]

puts a**2