[Newbies] Float comparsion

[Camillo Bruni]

hehe thanks for the vivid response ;)
Well then I'll use closeTo, I don't really need a very accurate  
comparison.
But since I want to create a Renderer the performance will be the  
biggest
problem. Well thats also why I've chosen Squeak ;).


thanks for the responses


Am 27.02.2009 um 13:51 schrieb Bert Freudenberg:

> The Epsilon class variable is used only when the primitives for some  
> float functions are not available, in which case they are  
> approximated to that precision. Using that same epsilon for  
> something else is as meaningless as the 0.0001 in #closeTo:.
>
> The epsilon really depends on your application.
>
> - Bert -
>
> On 27.02.2009, at 13:41, Oscar Nierstrasz wrote:
>
>>
>> Yes, we looked at that, but closeTo: uses a much larger epsilon  
>> than Float's class variable Epsilon.
>>
>> I suggested Camillo wrote an extension method similar to closeTo:  
>> but using the existing Epsilon (or an arbitrary one as an  
>> additional parameter).
>>
>> Is that the right thing to do?
>>
>> - on
>>
>> On Feb 27, 2009, at 13:34, Lukas Renggli wrote:
>>
>>> Hi Camillo ;-)
>>>
>>> Use the method #closeTo: instead of #=. Comparing floats with #=
>>> almost never works.
>>>
>>> Although "(Float halfPi / 2) tan" is printed as 1.0, it is not  
>>> exactly
>>> 1.0 due to rounding errors in the calucaltaion and/or the internal
>>> representation.
>>>
>>>  (Float halfPi / 2) tan - 1.0 --> -1.110223024625156e-16
>>>
>>> Lukas
>>>
>>> -- 
>>> Lukas Renggli
>>> http://www.lukas-renggli.ch
>>> _______________________________________________
>>> Beginners mailing list
>>> Beginners at lists.squeakfoundation.org
>>> http://lists.squeakfoundation.org/mailman/listinfo/beginners
>>
>> _______________________________________________
>> Beginners mailing list
>> Beginners at lists.squeakfoundation.org
>> http://lists.squeakfoundation.org/mailman/listinfo/beginners
>
>
>
> _______________________________________________
> Beginners mailing list
> Beginners at lists.squeakfoundation.org
> http://lists.squeakfoundation.org/mailman/listinfo/beginners

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.squeakfoundation.org/pipermail/beginners/attachments/20090227/54d4a0e6/attachment-0001.htm