[ruby-core:39198] [Ruby 1.9 - Bug #4576] Range#step miss the last value, if end-exclusive and has float number

Issue #4576 has been updated by Vit Ondruch.

File 0001-Fix-the-ronding-error-causing-wrong-evaluation-of-ra.patch added

Usaku NAKAMURA wrote:
> =begin
>  Hello,
>  
>  In message "[ruby-core:35804] [Ruby 1.9 - Bug #4576] Range#step miss the last value, if end-exclusive and has float number"
>      on Apr.18,2011 12:06:24, <[e-mail]> wrote:
>  > test_step_ruby_core_35753 seems depend on platform.
>  > On i686-linux it fails.
>  
>  Ah, I doubt it. Thank you.
>  
>  
>  > May i partially revert an testcase of test_step_ruby_core_35753?
>  
>  No.
>  I guess that 1.5 stepping doesn't have error.
>  Please test r31304.
>  
>  
>  Regards,
>  -- 
>  U.Nakamura <[e-mail]>
> =end

Can we reopen this issue please? The fix of unit tests was wrong, fixing consequences instead of reasons. Moreover, it was not backported to 1.8.7, so we hit the issue again when preparing updated package for RHEL 6.2. You can find the discussion about the issue at [1] including proposed solution [2]. Could you please review and apply the attached patch and also backport it to 1.8.7?

[1] https://bugzilla.redhat.com/show_bug.cgi?id=733372
[2] https://bugzilla.redhat.com/attachment.cgi?id=520552
----------------------------------------
Bug #4576: Range#step miss the last value, if end-exclusive and has float number
http://redmine.ruby-lang.org/issues/4576

Author: Joey Zhou
Status: Closed
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: -


=begin
Hi, I find that:

* if: range.exclude_end? == true
* and: any one in [begin_obj, end_obj, step] is a true Float(f.to_i != f)
* and: unless begin_obj + step*int == end_obj
* then: the result will miss the last value.

for example:

 p (1...6.3).step.to_a # => [1.0, 2.0, 3.0, 4.0, 5.0], no 6.0
 p (1.1...6).step.to_a # => [1.1, 2.1, 3.1, 4.1], no 5.1
 p (1...6).step(1.1).to_a # => [1.0, 2.1, 3.2, 4.300000000000001], no 5.4

 p (1.0...6.6).step(1.9).to_a # => [1.0, 2.9], no 4.8
 p (1.0...6.7).step(1.9).to_a # => [1.0, 2.9, 4.8]
 p (1.0...6.8).step(1.9).to_a # => [1.0, 2.9, 4.8], no 6.7

Maybe the #step is ok on integers, but there's something wrong if the range is end-exclusive and contain float numbers.
=end



-- 
http://redmine.ruby-lang.org