handling T.min the right way

[BCS]

Lionello Lunesu wrote:
> Lionello Lunesu wrote:
> 
>> Frits van Bommel wrote:
>>
>>> Lionello Lunesu wrote:
>>>
>>>> "Andrei Alexandrescu (See Website For Email)" 
>>>> <SeeWebsiteForEmail at erdani.org> wrote in message 
>>>> news:45FEE0BC.4000407 at erdani.org...
>>>>
>>>>> The right way is to have T.min always return the minimum value 
>>>>> (duh) and define a separate property T.min_positive.
>>>>
>>>>
>>>> Isn't this value sometimes also called "epsilon"? I think 
>>>> double.epsilon sounds quite nice :)
>>>
>>>
>>> Epsilon is already used for a related concept:
>>> ".epsilon -- smallest increment to the value 1" 
>>> (http://www.digitalmars.com/d/property.html)
>>
>>
>> Huh, I thought it sounded familiar.
>>
>> So epsilon is such that 1.0+epsilon!=1.0, and the 'min' we're talking 
>> about is such that 0.0+min_positive!=0.0 ? I didn't know these were 
>> both useful values.... I wonder how they're actually being used.
>>
>> L.
> 
> 
> Nevermind, I think I get it. epsilon reflects the smallest exponent, 
> whereas min_positive represents the reflects the resolution of the 
> mantissa.

Actually I think that is backwards. Epsilon reflects the number of bits 
in the mantissa and min_positive reflects the smallest exponent.

> 
> Both have bad names though. What terminology do mathematicians use for 
> these 'constants'?
> 
> L.