From: "marcandre (Marc-Andre Lafortune)" <ruby-core@...>
Date: 2013-04-21T07:41:04+09:00
Subject: [ruby-core:54484] [Backport 200 - Backport #8299][Open] Minor error in float parsing


Issue #8299 has been updated by marcandre (Marc-Andre Lafortune).

Status changed from Rejected to Open
Priority changed from Low to Normal

Actually, this is a bug.

1) Float#to_s must be minimal while round-tripping. This is clearly not the case in the given examples.

2) Float#to_s must be platform independent

On OS X, I get the correct string conversion.
$ ruby -v -e 'p(-1.1505945E-5)'
ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-darwin10.8.0]
-1.1505945e-05
ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-darwin10.8.0]
-1.1505945e-05

----------------------------------------
Backport #8299: Minor error in float parsing
https://bugs.ruby-lang.org/issues/8299#change-38790

Author: bobjalex (Bob Alexander)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


I encountered a float that either parses [slightly] differently (or converts to string differently) in Ruby than it does in Python or Java. This looks like a  Ruby bug since the result "looks" incorrect.

It is easily reproduced by entering the magic number (-1.1505945E-5) into irb. It behaves the same in 2.0 and 1.9. I'm using Windows.

Below is an irb session that demonstrates. Also included are JRuby and Python trials that show better behavior.

This issue is not causing me any problems, but just in case someone there is interested in looking into it...

Bob

>ruby -v
ruby 2.0.0p0 (2013-02-24) [i386-mingw32]

>irb
irb(main):001:0> RUBY_VERSION
=> "2.0.0"
irb(main):002:0> -1.1505945E-5
=> -1.1505945000000001e-05

>ruby19 -v
ruby 1.9.3p392 (2013-02-22) [i386-mingw32]

>irb19
irb(main):001:0> RUBY_VERSION
=> "1.9.3"
irb(main):002:0> -1.1505945E-5
=> -1.1505945000000001e-05
irb(main):002:0>

>jirb
irb(main):001:0> -1.1505945E-5
=> -1.1505945e-05

>python
Python 2.7.4rc1 (default, Mar 24 2013, 14:34:32) [MSC v.1500 32 bit (Intel)] on
win32
Type "help", "copyright", "credits" or "license" for more information.
>>> -1.1505945E-5
-1.1505945e-05
>>> repr(-1.1505945E-5)
'-1.1505945e-05'




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