I mean the number zero, as you described (sorry, I was using my proper English and writing out the number instead of writing 0).
You can open an issue for it if you want. I'm not convinced at this point what exactly it should do, if anything. Definitely doing something more advanced will require better deduction on the part of the assumptions system. Aaron Meurer On Thu, May 30, 2013 at 4:48 PM, Lucas Wilkins <[email protected]> wrote: > Do you mean sympy.core.numbers.Zero? Or do mean the general problem that > symbolically, zero is often the same as lack of objects? > > Should I flag it as an issue? > > On Thursday, 30 May 2013 21:46:53 UTC+1, Lucas Wilkins wrote: >> >> Hi, I've found some inappropriate behaviour of the solve function. >> >> >>> x,y = symbols("x y", real=True, nonnegative=True) >> >>> solve(y-x**2,x) >> [-sqrt(y), sqrt(y)] >> >> The only non-negative case where both sqrt(y) and -sqrt(y) should be >> solutions is where y=0, in which case they are equal and not different after >> all. It's quite annoying if there should be a single solution of zero! >> >> It should really work like positives: >> >> >>> x,y = symbols("x y", real=True, positive=True) >> >>> solve(y-x**2,x) >> [sqrt(y)] >> >> I didn't submit an issue because I was not sure if it was deliberate >> (perhaps for making floats work properly?). >> >> :L >> >> > -- > 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?hl=en-US. > For more options, visit https://groups.google.com/groups/opt_out. > > -- 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?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
