Hi,

On 23 May 2011 20:46, Aaron S. Meurer <asmeu...@gmail.com> wrote:

>
> On May 23, 2011, at 12:40 PM, Chris Smith wrote:
>
> > Aaron S. Meurer wrote:
> >>> On May 22, 2011, at 9:31 PM, Renato Coutinho wrote:
> >>>
> >>>> On Mon, May 23, 2011 at 12:28 AM, Mateusz Paprocki
> >>>> <matt...@gmail.com> wrote:
> >>>>> Hi,
> >>>>>
> >>>>> On 23 May 2011 05:18, smichr <smi...@gmail.com> wrote:
> >>>>>>
> >>>>>> Will list(e.free_symbols) be OS independent?
> >>>>>
> >>>>> .free_symbols is implemented using sets so it is platform (hash)
> >>>>> dependent (I mean order of elements).
> >>>>
> >>>> But sets don't have any ordering (except for printing or iterating,
> >>>> but you shouldn't use it). I think sorted(list(e.free_symbols))
> >>>> should
> >>>> be safe.
> >>>>
> >>>> Cheers,
> >>>> Renato
> >>>
> >>> No, sorted uses __le__, which for symbols uses the hash, so that too
> >>> will be platform dependent (granted it's better than list(set),
> >>> which might return a different thing within the same session).
> >>>
> >>> Why do you need to have a list instead of a set?
> >>>
> > If you have `solve([x+y-3,x-y-1])` you need an unambiguous way to return
> the tuples if you aren't going to return the results with the symbols. You
> could get set([Tuple(1, 2)]) or set([Tuple(2, 1)]) so you need a way to
> internally send back something unambiguous.
> >
>
> I think it should just return the result with the symbols.
>

Or use sorted_key to get hash independent ordering.


>
> Aaron Meurer
>
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>
Mateusz

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