From: Michael Garriss <mgarriss@...>
Date: 2003-08-12T11:22:02+09:00
Subject: Re: NaN and Inifinity

Dan Doel wrote:

> Scott Thompson wrote:
>
>>> irb(main):015:0> a = Math::log(-1)
>>> => NaN
>>> irb(main):016:0> a.class
>>> => Float
>>> irb(main):017:0> b = "NaN".to_f
>>> => NaN
>>> irb(main):018:0> b.class
>>> => Float
>>> irb(main):019:0> b.nan?
>>> => true
>>
>>
>>
>> Hrrrm... Okee dokey.  I tried something like that and I get
>>
>> irb(main):002:0> b = "NaN".to_f
>> => 0.0
>> irb(main):003:0> b.nan?
>> => false
>>
>> There must be something wacky with my Ruby. :-)
>>
>> Scott
>
>
> It's not just you. Happens to me, too, using Ruby 1.8.0pre9 (I 
> believe) mswin32 build.
>
> Then again, Math::log(-1) throws a domain error for me.
>
> If worse comes to worst you could always initialize with 
> Math::log(-1), since that returns
> what you want.
>
> - Dan
>

I got one for you.  I was getting this:

irb(main):001:0> a = Math::log(-1)
=> 3.141592653589793i
irb(main):002:0> a.class
=> Complex
irb(main):003:0> b = "NaN".to_f
=> 0.0
irb(main):004:0> b.class
=> Float
irb(main):005:0> b.nan?
=> false

Then I realized that I start irb with the -m option.  Hmmm.