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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Indexes: why signed instead of unsigned?
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Tue, 11 May 2010 11:35:17 -0400
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2010/5/11 Adolfo Rodríguez Tsouroukdissian <adolfo.rodriguez@xxxxxxxxxxxxxxxxx>:
>
>
> On Tue, May 11, 2010 at 5:07 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
> wrote:
>>
>> I tend to agree that we need ptrdiff_t instead of int. I'd suggest:
>>
>> typedef std::ptrdiff_t idx;
>>
>> so we get something short to type.
>>
>> There remains the question of signed vs. unsigned. In other words,
>> ptrdiff_t vs. size_t. I'm totally unable to decide either way. Help!
>
> It would be nice to see if there is consensus in this respect among other
> linear algebra packages. What do the more common alternatives use?
> Here's a couple of examples I found by a quick search:
> - blas uses signed integers:
> http://www-sfb288.math.tu-berlin.de/~jtem/blas/api/index.html
Bing, this is very important indeed!
> - boost::numeric::ublas uses unsigned integers:
> http://www.boost.org/doc/libs/1_43_0/libs/numeric/ublas/doc/matrix.htm
Boost::ublas not comparable in importance to BLAS...
> - OpenCV use signed integers:
> http://opencv.willowgarage.com/documentation/cpp/basic_structures.html#mat
good to know.
Benoit
>
> Adolfo
>
>>
>> Benoit
>>
>> 2010/5/11 joel falcou <joel.falcou@xxxxxx>:
>> > Rohit Garg wrote:
>> >>
>> >> This will become an issue when people start using bigger datasets than
>> >> 2GB. At a minimum, we need a eigen_size_t typedef somewhere for easy
>> >> portability. Using long throughout in 32 bit machines doesn't make
>> >> sense.
>> >>
>> >
>> > Isn't it what ptrdiff_t supposed to be ? biggest signed int on the
>> > platform
>> > .
>> >
>> > --
>> > ___________________________________________
>> > Joel Falcou - Assistant Professor
>> > PARALL Team - LRI - Universite Paris Sud XI
>> > Tel : (+33)1 69 15 66 35
>> >
>> >
>> >
>> >
>> >
>>
>>
>