From: Yusuke ENDOH <mame@...>
Date: 2011-09-17T16:14:10+09:00
Subject: [ruby-core:39606] Re: [Ruby 1.9 - Bug #4576] Range#step miss the last value, if end-exclusive and has float number

Hello,

2011/9/17 NARUSE, Yui <naruse@airemix.jp>:
> In my current understanding, the error is
> fabs(beg) * epsilon + fabs(unit) * epsilon * n + fabs(end) * epsilon
> = (fabs(beg) + fabs(end) + fabs(end-beg)) * epsilon
> // ignore error over unit*n -> end-beg
> But the correct error may be less than it.


I have no understanding of the error, but your patch does not
work in this case:

  e = 1.0 + 1E-12
  p (1.0 ... e).step(1E-16).all? {|n| n < e }  #=> false
  p (1.0 ... e).step(1E-16).to_a.last == e     #=> true

-- 
Yusuke Endoh <mame@tsg.ne.jp>