On Thu, Apr 9, 2009 at 12:22 AM, Stan Schymanski <schym...@gmail.com> wrote: > > Dear all, > > I encountered some mysterious problems earlier when I used .subs(locals > ()), where some global variables such as pi and e were lost (see. e.g. > thread > http://groups.google.com/group/sage-support/browse_thread/thread/0f1086c43611242a?). > > Now I found an example that demonstrates this a bit better: > > sage: var('a b c blah') > sage: varsdict = dict(blah = exp(b)) > sage: y = (1/blah*a - sin(pi*c)).subs(varsdict) > sage: y.arguments() > (a, b, c) > > But, doing the same thing using .subs(locals()) gives: > > sage: var('a b c') > sage: blah = exp(b) > sage: y = (1/blah*a - sin(pi*c)).subs(locals()) > sage: y.arguments() > (a, b, c, e, pi) > > Here, sage suddenly seas e and pi as variables, which leads to all > sorts of problems when using fast_float or simplifying, or plotting. > The original behaviour is only restored after restarting the notebook! > E.g. using the previous approach again now gives: > > sage: var('a b c blah') > sage: varsdict = dict(blah = exp(b)) > sage: y = (1/blah*a - sin(pi*c)).subs(varsdict) > sage: y.arguments() > (a, b, c, e, pi) > > Shall I open a ticket for this or is it intended behaviour?
I have a guess as to what is going on. Perhaps it's using maxima to do the substitution, and so it tells maxima that every local variable name is actually a symbolic variable? If this is the problem, I'm not sure how to fix it, though. Carl --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
