This seems to be a follow-up to this <https://ask.sagemath.org/question/46819/numerical-integration-and-plot-failing/> ask.sahemath.org question.
1. As already pointed out by Serge Lelièvre, this anomaly doesn't happent in a Python3-based Sage. Possibly, the behaviour of floats raised to a negative fractional power are different ? 2. I took the liberty of pointing future ask.sagemath readers to this sage-devel thread for future reference. HTH, Le vendredi 5 juillet 2019 22:58:12 UTC+2, Piotr Sniady a écrit : > > Dear Developers, > > the code below produces a function which for any real u<3 gives as value > \pi/3. > One can check that for any given number Sage has no problems to evaluate > this function > and that it gives the right value. > > For strange reason I cannot integrate this function numerically. > Also, I cannot plot this function. > > Magically, while for any given value Sage has no problems to give a > complex root of a negative number, > for numerical integration the behavior of the root changes. > > Any help would be appreciated. > > Yours, > > Piotr > > > > def F(u): > return arg( (-3 + u )^(1/3) ).n() > > numerical_integral(F,1,2) > > > > > Error message: > > negative number cannot be raised to a fractional power > > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/25731a37-ae73-470b-b943-6da6f1d9ef4e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
