Le mercredi 20 avril 2011 à 13:16 -0600, Aaron S. Meurer a écrit : > > On Apr 20, 2011, at 1:04 PM, Mateusz Paprocki wrote: > > > Hi, > > > > On 20 April 2011 11:55, Aaron S. Meurer <[email protected]> wrote: > > The Solution class is indeed a good idea. > > > > I think it would be best to have a unified data structure > > independent of the number of solutions. The reason is that > > it is not clear from the outset how many solutions an > > equation or system of equations will have. That is why I > > think it would be better to have a list always or a > > dictionary always (or a list of dictionaries always). The > > list of dictionaries idea is one of the better ones, in my > > opinion. > > > > > > This is what Mathematica does (for example) (it gives a list of > > rules, which is a list of dicts in Python's terminology). There is > > one more issue that has to be taken into account: currently it's not > > easy to substitute results from solve() back to the original > > equation/set of equations (in a systematic way). > > > If you have a list of dictionaries, you can just do > > > sol = solve(expr, vars) > expr.subs(sol[0]) > expr.subs(sol[1]) > … > > > or just > > > [expr.subs(i) for i in sol] > > > because subs works with a dictionary. Actually, looking at it this > way, this data structure is far superior to any of the others. > That won't work if there's an infinite number of solutions.
> > And this is another advantage that a Solution class could offer. We > could just make expr.subs(Solution) work as you would expect it to. > Actually, I don't know what expr.subs(Solution) is supposed to do and I would expect it to raise an exception. -- 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.
