On Tuesday, January 28, 2014 8:29:16 PM UTC-5, Robert Jacobson wrote: > > I am having difficulty using Piecewise(). For example, I can define the > following: > t = Piecewise([[(-oo, -1), 0*x^0], [(-1, 0), 1+x], [(0, 1), 1-x], [(1, oo > ), 0*x^0]], x) > but then evaluating t(-100) fails. >
Hmm, this works for me. What version of Sage are you using? > I can modify the above to have a finite domain: > t = Piecewise([[(-10, -1), 0*x^0], [(-1, 0), 1+x], [(0, 1), 1-x], [(1, 10 > ), 0*x^0]], x) > This seems to evaluate correctly within its domain, but I can't plot it, > say, with this (or variations thereof): > plot(t(x), x, -4, 4) > > Piecewise is an amalgam of some very old code/methods and some other stuff. Consequently, one has to read its documentation fairly carefully to see what might need to be done. See http://trac.sagemath.org/ticket/11225 for just some of the quirks. In this case, you need to plot sage: plot(t).show(xmin=-4,xmax=4) because rather than plotting t, it calls t.plot and that changes things quite a bit. Also sage: t(x) ValueError: ... since Piecewise objects are still not symbolic. I'm sorry this is still the case. See http://trac.sagemath.org/ticket/14801 for a prototype for a new way to do all this. Luckily, you should be able to do what you want, but not with a unified syntax, it is true. - kcrisman -- 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 http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/groups/opt_out.
