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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: Negative zero doesn't exist
Date: Sun, 1 Jun 2025 12:05:28 +0300
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On 2025-05-31 11:46:37 +0000, Fred. Zwarts said:

> Op 30.mei.2025 om 16:10 schreef Richard Damon:
>> On 5/30/25 5:09 AM, Richard Heathfield wrote:
>>> On 30/05/2025 09:16, Mikko wrote:
>>> 
>>> <snip>
>>> 
>>>> However, when working with approximate values it may be useful
>>>> to know whether the true value is positive or negative even
>>>> when for other values a little more or less is insignifcant.
>>>> One such case is temperature where the difference between -0.1
>>>> °C can be significantly different from +0.1 °C for practical
>>>> purpoises even when the difference between, say, 5 °C and 6 °C
>>>> isn't.
>>> 
>>> Practical porpoises will avoid -0.1°C because it makes swimming too difficult.
>>> 
>> 
>> But porpoises swim in salt water, which will still be liquid at that 
>> temperature, but colder than they like.
>> 
>> 
>> Minus 0 in IEEE is mostly an artifact of the representation, being a 
>> sign + magnatude representation.
> 
> Other systems have even more possibilities to represent 0. E.g., pencil 
> and paper can be used to represent 0 as 0, 0.0, 0.00, 000, 00.0, 0.0E0, 
> -0.0, etc. It is not uncommon that a single number can be represented 
> in different ways in certain systems. Usually, nobody makes a problem 
> of it, as it is understood that always the same number is represented.

In the above examples it is easy to see that all expressions donote the
same number. But there are (rational or real) numbers that are not that
easy, for example 2:45, 2.75, and 2 3/4.

-- 
Mikko