Jason Grout wrote: > Mike Witt wrote: >> On 08/21/2008 06:55:48 PM, Joel B. Mohler wrote: >>> On Thursday 21 August 2008 01:58:23 pm Mike Witt wrote: >>>> I'm looking for a work-around for the situation where I would normally >>>> call parametric_plot (or plot, for that matter) with a function, and in >>>> some particular case that function turns out to evaluate to a constant. >>>> >>>> For example: >>>> >>>> sage: def f(a,b): return e^(a+b*I) >>>> ....: >>>> sage: parametric_plot([real(f(x,1)),imag(f(x,1))], -pi, pi) >>>> >>>> Works as expected >>>> >>>> sage: parametric_plot([real(f(x,-1)),imag(f(x,-1))], -pi, pi) >>>> >>>> Works as expected >>>> >>>> sage: parametric_plot([real(f(x,0)),imag(f(x,0))], -pi, pi) >>>> >>>> Gives a page full of errors, which I interpret to mean that there >>>> was a problem plotting because imag(f(x,0)) evaluates to a constant. >>>> >>>> I believe that this is the same issue described in: >>>> >>>> http://trac.sagemath.org/sage_trac/ticket/2410 >>> I'm the person that entered the trac ticket and the point of that trac >>> ticket >>> is precisely the (mis-)functionality you are describing. I'm truly >>> mystified by the other responses in this thread. To me, this is an obvious >>> bug... >>> >>> -- >>> Joel >> Thanks Joel. I was beginning to wonder if I was nuts. Just to summarize what >> I've found out so far. The work-arounds suggested by David Joyner, Mike >> Hansen, >> and Carl Witty all work under certain assumptions, but none of the three >> provides a completely general fix as far as I can see. Using a combination of >> the techniques I am able to do what I want. But I am for whatever it's worth >> I'd certainly like to add my vote that tickets #2409 and #2410 should get >> attention. This issue with parametric_plot is certainly *very* confusing >> to a newcomer. > > > Here's yet another method: > > sage: from sage.ext.fast_eval import fast_float > sage: plot(fast_float(1), -1, 2) > sage: parametric_plot((fast_float(1),t),-12,12) > > > Now, why in the world the plot functions aren't calling fast_float, I > don't know. I thought that's what they did. I'm looking into it for a > few minutes, at least. >
Okay, apparently no one has had time to implement it. Calling fast_float will solve the issue, as it is solved in parametric_plot3d, for example. The new ticket is #3952. I've also posted a patch on #2410 which corrects a bug in the exception handling so that you get an sensible exception instead of the nonsensical indexing exception that you get now. Thanks, Jason --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
