Maybe a kind Japanese reader can provide the gist of [ruby-dev:41061]
to explain why was Float#rationalize removed?

I would also appreciate opinions as to why it wouldn't be a net
improvement if to_r used the rationalize algorithm and some other
methods were provided for anyone wanting the value of the
representation (e.g. Float#representation which would return [sign,
mantissa, significand] and/or Float#representation_to_r would give the
rational corresponding to the internal representation of that float)