# sage-devel

[Prev] Thread [Next] | [Prev] Date [Next]

#### [sage-devel] Re: problem with complex_plot and real_part Burcin Erocal Fri Jun 26 06:00:29 2009

On Fri, 26 Jun 2009 08:27:44 -0300 Golam Mortuza Hossain <[EMAIL PROTECTED]> wrote: > > Hi > > On Thu, Jun 25, 2009 at 11:31 PM, Nick > Alexander<[EMAIL PROTECTED]> wrote: > > > > Can someone verify that this is a bug? Any hope a fix? (This is > > with sage-4.0.2 on sage.math.) > > > > {{{ > > sage: complex_plot((x^2 + I).sqrt().real_part(), (-2, 2), (-2, 2)) > > --------------------------------------------------------------------------- > ... > > RuntimeError: cannot find SFunction in table > > }}} > > It seems, its not just complex_plot issue. It is happening for other > plots. For example, the following works fine in 3.4 but fails with > the same error in 4.0.2 > ----- > sage: x,y=var('x,y'); plot3d( log(x+I*y).imag(), (x,-2,2), (y,-2,2)) > ... > RuntimeError: cannot find SFunction in table > ----- sage: %debug > /home/burcin/sage/sage-4.0.2.rc0/expression.pyx(3115)sage.symbolic.expression.Expression.operator > (sage/symbolic/expression.cpp:15268)() ipdb> u > /home/burcin/sage/sage-4.0.2.rc0/local/lib/python2.5/site-packages/sage/symbolic/expression_conversions.py(206)__call__() 205 --> 206 operator = ex.operator() 207 if operator is None: ipdb> print ex arctan2(real_part(y) + imag_part(x), real_part(x) - imag_part(y)) Both of these fail because Sage doesn't define a symbolic arctan2 function. There is instead a simple wrapper around arctan in sage/functions/trig.py: sage: arctan2(x,y) arctan(x/y) It's possible that this worked on 4.0, and I broke it with #6244. I opened a ticket: http://trac.sagemath.org/sage_trac/ticket/6421 I don't think I will have time to fix this in the next few days. Feel free to replicate one of the Function_* classes in sage/functions/trig.py to define a new symbolic function called arctan2, with ginac conversion atan2. Thanks. Burcin --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [EMAIL PROTECTED] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---

[sage-devel] problem with complex_plot and real_partNick Alexander

[sage-devel] Re: problem with complex_plot and real_partDavid Joyner[sage-devel] Re: problem with complex_plot and real_partGolam Mortuza Hossain