Safely compare floats

float_approximation.rb

## you presumably already know that this returns false, because of the way floats are stored:
0.1 + 0.2 == 0.3
# => false


# we can create a more useful way of comparing floats that matches what humans would expect:
class Float
  def =~(number, tolerance = 0.0001)
    (self - number).abs < tolerance
  end
end

## here's an example of typical usage:
0.1 + 0.2 =~ 0.3
# => true


## if you need to change the tolerance, 
## use a dot like with normal methods:
(0.1 + 0.2).=~ 0.3, 0.00000000001