It is a classical issue, known as Casus irreducibilis <https://en.wikipedia.org/wiki/Casus_irreducibilis>, that the algebraic expressions of the roots of an irreducible cubic polynomial involve complex expressions even in case the roots are real. (See also this <https://github.com/sympy/sympy/issues/14690> for more information.)
Kalevi Suominen On Wednesday, October 3, 2018 at 9:03:22 AM UTC+3, Cesar Gomes wrote: > > Hello everyone! > > While trying to find the zeros of the following polynomial: > > > q = (-2/15)*x**3 + (23/10)*x**2 - (47/30)*x - 21 > > > Sympy is returning 3 complex roots, which makes no sense since there are 3 > real roots. Using nsolve the results are as expected. > > > What am I missing? > > > I'm using Python 3.6.4 and IPython 6.2.1 on OS X Mojave. > -- 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 https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/8ccf7f66-980b-486f-aa04-d50bd8d44560%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
