Hi, On 16 June 2011 08:32, Matthew Rocklin <[email protected]> wrote:
> Hi everyone, I have a question about turning inequalities on symbols into > Intervals. > > I am currently able to do (and get much use out of) this > >>> reduce_poly_inequalities([[x>=0]], x, relational=False) > which returns the correct interval: > [0, ∞) > > I would like to be able to do this: > >>> reduce_poly_inequalities([[x>=y]], x, relational=False) > and get this > [y, ∞) > but instead I get this > NotImplementedError: inequality solving is not supported over ZZ[y] > > which is an error I think to preempt an error being caused in the > sympy.polys.rootoftools.RootOf class although at this point I'm in over my > head. > > Should I: > 1) investigate this more and see if I can fix things? > 2) make an issue? > 3) look for another way to solve my problem because this will be difficult > to fix? > It depends what you really want to do (you just gave one trivial example which makes it hard to give any advice based on this). In general solving multivariate inequalities is very hard and implies using Groebner bases and cylindrical algebraic decomposition. Trivial cases can be implemented by pattern matching (but computer algebra is not about trivial cases). The current limitations in inequality solver are due to the fact that we can only solve polynomials with rational coefficients in full generality in SymPy (thanks to complex root isolation algorithms and RootOf). > > Best, > -Matt > > -- > 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. > Mateusz -- 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.
