Forum: Ruby Bug in Float? (was: NaN Error)

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Tim P. (Guest)
on 2007-04-17 22:42
(Received via mailing list)
I ran across some peculiar behavior yesterday when working with large
floating point values. Here is a small script that demonstrates the
behavior. My question is, is this the expected behavior or is this a
bug in Float?

> cat float_bug.rb
puts "ruby #{RUBY_VERSION} " +
     "(#{RUBY_RELEASE_DATE} patchlevel #{RUBY_PATCHLEVEL}) " +
     "[#{RUBY_PLATFORM}]"

puts "Float::MAX = #{Float::MAX}"
puts "1.0e+300 = #{1.0e+300}"
puts "1.0e+301 = #{1.0e+301}"
puts "1.0e+308 = #{1.0e+308}"
puts "1.0e+700 = #{1.0e+700}"

# EOF


When I run this script on my Windows machine, it produces the output I
would expect -- i.e. numbers above Float::MAX are "Infinity" and
numbers below Float::MAX are valid floating point numbers.

> ruby -w float_bug.rb
ruby 1.8.5 (2006-12-25 patchlevel 12) [i386-cygwin]
Float::MAX = 1.79769313486232e+308
1.0e+300 = 1.0e+300
1.0e+301 = 1.0e+301
1.0e+308 = 1.0e+308
1.0e+700 = Infinity


Now, when I run the exact same script on a Solaris machine, some odd
things start to happen

> ruby -w float_bug.rb
ruby 1.8.5 (2006-12-25 patchlevel 12) [sparc-solaris2.8]
Float::MAX = 1.79769313486232e+308
1.0e+300 = 1.0e+300
1.0e+301 = NaN
1.0e+308 = NaN
1.0e+700 = 8.55180271847103e+116


Whey are valid floats being treated as NaN?  Better yet, why does
1.0e+700 get evaluated to 8.5518027e+116?


Once more on the Windows 1-click installed version of Ruby.

> ruby -w float_bug.rb
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]
Float::MAX = 1.79769313486232e+308
1.0e+300 = 1.0e+300
1.0e+301 = NaN
1.0e+308 = NaN
1.0e+700 = 1.0e+189


Any thoughts on this one?  I encourage you to copy the float_bug.rb
script and try it out for yourself.

Blessings,
TwP
Dan Stevens (IAmAI) (Guest)
on 2007-04-17 23:25
(Received via mailing list)
$ ruby float_bug.rb
ruby 1.8.5 (2006-08-25) [i486-linux]
Float::MAX = 1.79769313486232e+308
1.0e+300 = 1.0e+300
1.0e+301 = 1.0e+301
1.0e+308 = 1.0e+308
1.0e+700 = 1.02189775487683e+36
Gavin K. (Guest)
on 2007-04-17 23:46
(Received via mailing list)
On Apr 17, 11:41 am, "Tim P." <removed_email_address@domain.invalid> wrote:
> Once more on the Windows 1-click installed version of Ruby.
>
> > ruby -w float_bug.rb
>
> ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]
> Float::MAX = 1.79769313486232e+308
> 1.0e+300 = 1.0e+300
> 1.0e+301 = NaN
> 1.0e+308 = NaN
> 1.0e+700 = 1.0e+189

Further, (Windows, 1-click), same version:

C:\>ruby -v
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]

C:\>irb -v
irb 0.9.5(05/04/13)

C:\>irb
irb(main):001:0> 1.0e+800
=> 1.0e+289
irb(main):002:0> 1.0e+900
=> NaN
irb(main):003:0> 1.0e+1000
=> NaN
irb(main):004:0> 1.0e+1100
(irb):4: warning: Float 1.0e+1100 out of range
=> Infinity
Chris S. (Guest)
on 2007-04-18 01:21
(Received via mailing list)
On Apr 17, 12:41 pm, "Tim P." <removed_email_address@domain.invalid> wrote:
>
> numbers below Float::MAX are valid floating point numbers.
> Now, when I run the exact same script on a Solaris machine, some odd
>
> 1.0e+301 = NaN
> 1.0e+308 = NaN
> 1.0e+700 = 1.0e+189
>
> Any thoughts on this one?  I encourage you to copy the float_bug.rb
> script and try it out for yourself.
>
> Blessings,
> TwP

On OS X 10.4.9

mvb:~ cms$ ruby float_bug.rb
ruby 1.8.6 (2007-03-13 patchlevel 0)
Float::MAX = 1.79769313486232e+308
1.0e+300 = 1.0e+300
1.0e+301 = NaN
1.0e+308 = NaN
1.0e+700 = 0.0

And my Xubuntu box (pre-RUBY_PATCHLEVEL apparently):

ruby 1.8.4 (2005-12-24)[i486-linux]
Float::MAX = 1.79769313486232e+308
1.0e+300 = 1.0e+300
1.0e+301 = 1.0e+301
1.0e+308 = 1.0e+308
1.0e+700 = 0.0
Nobuyoshi N. (Guest)
on 2007-04-18 05:42
(Received via mailing list)
Hi,

At Wed, 18 Apr 2007 03:41:22 +0900,
Tim P. wrote in [ruby-talk:248272]:
> I ran across some peculiar behavior yesterday when working with large
> floating point values. Here is a small script that demonstrates the
> behavior. My question is, is this the expected behavior or is this a
> bug in Float?

Thank you, fixed now.
Tim P. (Guest)
on 2007-04-18 18:57
(Received via mailing list)
On 4/17/07, Nobuyoshi N. <removed_email_address@domain.invalid> wrote:
>
Thank you very much, Nobu.

TwP
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