According to Serge Lelièvre, the proble doesn't occur when ran under a Python3-based Sage. He advises to run such a Sage, hich seems a bit early, IMHO?
Advice ? Le jeudi 6 juin 2019 11:04:27 UTC+2, Emmanuel Charpentier a écrit : > > This ask.sagemath question > <https://ask.sagemath.org/question/46819/numerical-integration-and-plot-failing/> > seems > to raise a genuine bug. Perusing Trac doesn't raise muc relevant, possibly > except for Trac#24428 <https://trac.sagemath.org/ticket/24428> and > Trac#21754 <https://trac.sagemath.org/ticket/21754>. > > From my comment to the ask.sagemath question : > > Indeed : > sage: var("y,z") > (y, z) > sage: cauchy(z)=solve(z*y^3 +y^2 - 2*z*y+2 ,y)[0].rhs() > sage: def foo(u):return(arg(cauchy(u)).n()) > sage: [foo(t) for t in (1,1.1..2)] > [0.828222717321238, > ## Snip... > 0.377665318352514] > Therefore, this function *can* be evaluated. But : > sage: plot(foo,(1,2)) > verbose 0 (3635: plot.py, generate_plot_points) WARNING: When > plotting, failed to evaluate function at 200 points. > verbose 0 (3635: plot.py, generate_plot_points) Last error message: > 'negative number cannot be raised to a fractional power' > Launched png viewer for Graphics object consisting of 0 graphics > primitives > ... not in `plot`. Trying to plot symbolically yelds : > TypeError: Cannot evaluate symbolic expression to a numeric value. > A bug, IMHO. > > Can someone confirm this and, possibly, give me hints as how to flag this > ticket efficiently ? > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/12729167-d8dc-490f-b02c-b710111a9b0f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
