numerical guys brain needed :)

> hi guys
>
> what your take on
>
>        http://code.google.com/p/pharo/issues/detail?id=2968
>
> Stef
>
> "The same value in a LargePositiveInteger and a SmallInteger will not compare properly. The same value in two LargePositiveIntegers will not compare properly, if their byte sizes are different. I think the problem is in Integer>>#digitCompare: It gives incorrect results if the digitLengths are different between receiver and arg. This bug cost me about a day to find and fix. Maybe it has been addressed in a newer image/vm but I thought I would offer my fix to save someone else some time if it hasn't been dealt with yet. (I searched all issues)
>
> Pharo image: Pharo1.0-10508-rc2dev10.01.2.image
> Pharo core version: Pharo-1.0-10508-rc2 Latest update: #10508
> Virtual machine used: <Squeak 4.2.5b1 - Mac OSX>
>
>
> Steps to reproduce:
> 1.
>
> (Integer new: 6 neg: false) = (Integer new: 8 neg: false) "0 = 0 should return true"
>
>
> 2.
>
> | int |
> int := Integer new: 6 neg: false.
> int digitAt: 1 put: 6.
> ^int = 6     "6 = 6 should return true""
> _______________________________________________
> Pharo-project mailing list
> [hidden email]
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
>

> my take is normalize integers after manipulating with them using digitAt:put:
> because if not, then you can't rely on size when comparing numbers,
> and comparison will become much slower, since you forced to always
> compare contents,
> regardless that size is different.
>
> On 18 September 2010 11:14, Stéphane Ducasse <[hidden email]> wrote:
>> hi guys
>>
>> what your take on
>>
>>        http://code.google.com/p/pharo/issues/detail?id=2968
>>
>> Stef
>>
>> "The same value in a LargePositiveInteger and a SmallInteger will not compare properly. The same value in two LargePositiveIntegers will not compare properly, if their byte sizes are different. I think the problem is in Integer>>#digitCompare: It gives incorrect results if the digitLengths are different between receiver and arg. This bug cost me about a day to find and fix. Maybe it has been addressed in a newer image/vm but I thought I would offer my fix to save someone else some time if it hasn't been dealt with yet. (I searched all issues)
>>
>> Pharo image: Pharo1.0-10508-rc2dev10.01.2.image
>> Pharo core version: Pharo-1.0-10508-rc2 Latest update: #10508
>> Virtual machine used: <Squeak 4.2.5b1 - Mac OSX>
>>
>>
>> Steps to reproduce:
>> 1.
>>
>> (Integer new: 6 neg: false) = (Integer new: 8 neg: false) "0 = 0 should return true"
>>
>>
>> 2.
>>
>> | int |
>> int := Integer new: 6 neg: false.
>> int digitAt: 1 put: 6.
>> ^int = 6     "6 = 6 should return true""
>> _______________________________________________
>> Pharo-project mailing list
>> [hidden email]
>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
>>
>
>
>
> --
> Best regards,
> Igor Stasenko AKA sig.
>
> _______________________________________________
> Pharo-project mailing list
> [hidden email]
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project