Le dimanche 24 avril 2011 à 07:33 +0545, Chris Smith a écrit : > Ronan Lamy wrote: > > Le dimanche 24 avril 2011 à 06:56 +0545, Chris Smith a écrit : > >> Vinzent Steinberg wrote: > >>> On 22 Apr., 16:53, "Chris Smith" <[email protected]> wrote: > >>>> I don't think we should get hung up on the fact that a set of > >>>> solutions should be returned as a literal set. How that set gets > >>>> represented/presented is just an interface issue. I don't see > >>>> anything wrong with presenting the set as elements in a list. The > >>>> list representation also allows for unambiguous, non-redundant > >>>> representation of the symbols and their values. And look at how > >>>> easy it is to make a replacement dictionary from a list as > >>>> compared to a dictionary...and I challenge anyone to try do the > >>>> same with a set in as compact a fashion: > >>> > >>>> h[4] >>> l=[(x,y),(1,2),(3,4)] > >>> > >>> You could use as well set([...]) here. There is no reason IMHO to > >>> use a list. > >> > >> In the list, that is a literal x and y -- symbols. That's what makes > >> the list less noisy: you get the symbols once, right at the start, > >> and then all the solutions. The dictionary is just too busy with > >> redundant symbols. Easy to use, hard to look at. > > > > But you know the symbols anyway since you just used them to get the > > list of solutions. So what's wrong with: > > > > You may have not requested an explicit set of symbols and are willing to take > whatever you get...in that case you need to know what you got. > > h[2] >>> solve([x+y-3,x**2+y-5]) > [(-1, 4), (2, 1)] > But that's just an unsafe convenience that should really only be used in interactive sessions, in which case you do know what the variables are.
> And if there are many symbols and you just want *some* solution, then > it's nice to let solve handle figuring out which set of symbols it can > solve for. > I'm not sure what it is you're suggesting, but it sounds like the "do what I mean" philosophy of coding, which produces "nice" results in simple cases and debugging nightmares in complex ones. It should be very easy to figure out what the variables are, basically just S(equations).free_symbols. -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
