From: Robert Klemme <shortcutter@...>
Date: 2009-04-29T06:55:02+09:00
Subject: Re: Detecting -0.0

On 28.04.2009 22:27, Jeff Schwab wrote:
> Thomas B. wrote:
>> Hello.
>>
>> I have a simple question - how to detect if a variable contains a Float
>> of value -0.0? Is there any special method for this, or any comparison
>> that distinguishes negative zero from a the regular zero?
> 
> NB: I'm not sure how portable this is.
> 
> def negative_zero?(number)
>   inverse = 1 / number.to_f
>   inverse < 0 && inverse.infinite? ? true : false

Why do you use the ternary operator to convert a boolean into a boolean?

> end
> 
> [ 0.0, # false
>  -0.0, # true
>  -1.0, # false
>   1.0  # false
> ].each do |f|
>   puts negative_zero?(f)
> end

My 0.02 EUR: normally there should not be any distinction between 0.0 
and -0.0.  Even though computer math is not the same as real math, the 
distinction does not seem to make sense to me.

Kind regards

	robert