ZERO, INF, NAN = 0.0, 1.0/0.0, 0.0/0.0 # Constants for testing
puts ZERO.finite? # => true: is this number finite?
puts INF.finite? # => false
puts NAN.finite? # => false
puts ZERO.infinite? # => nil: is this number infinite? Positive or negative?
puts INF.infinite? # => 1
puts -INF.infinite? # => -1
puts NAN.infinite? # => nil
puts ZERO.nan? # => false: is this number not-a-number?
puts INF.nan? # => false
puts NAN.nan? # => true