On Tue, Jan 13, 2015 at 5:08 PM, Sergey B Kirpichev <[email protected]> wrote:
> On Wed, Jan 14, 2015 at 08:55:59AM +1000, Amit Saha wrote: > > +1 for returning an empty list object - it's IMO user-friendly > > It's not friendly, it's broken. No way to distinguish between > "no solutions" and "I can't solve". > The current situation doesn't really distinguish that, though. It might give the impression that it does, but that's a false impression. Example: solve(cos(x) - x) raises NotImplementedError (it has solutions, but they are not analytic). solve(exp(x)) gives [] (it has no complex solutions). But solve(cos(x)**2 + sin(x)**2 - 1) gives [] (it is an identity, so all x solve it), and solve(floor(x) - 5) gives NotImplementedError (5.1 is a solution; this one is issue 7074) That's why I suggested a Solve object, which could contain that metadata in a more structured way (like Solve.is_all_solutions which would be True/False/None). But for now, solve() already returns an empty list in some cases, so it might as well always do that. > Exception - only way to workarround this, but in next solve > (see solveset.py) we should try unevaluated Solve object instead. > I agree let's try to do this better in the next iteration of solve(). Aaron Meurer > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/20150113230825.GA18048%40darkstar.order.hcn-strela.ru > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6LfZvvaYqvTpJmJAuiT%3DvTji6HpRiT1LLnax8WN2OH8nA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
