You are NOT wrong, your are right! I used to have a lot of problems from students when Maple simplified 2(x+y) to 2 (at least it used to).
John On 17/12/2007, William Stein <[EMAIL PROTECTED]> wrote: > > On Dec 17, 2007 5:32 AM, Joel B. Mohler <[EMAIL PROTECTED]> wrote: > > > > Hi, > > > > I don't think that the trac 1460 is really fixed. The bug just got moved > > around. > > http://trac.sagemath.org/sage_trac/ticket/1460 > > > > # sage 2.9 > > sage: t=var('t') > > sage: f=t*sin(0) > > sage: float(f(1)) > > # goes boom for a different reason than in 2.8.15 > > This is *not* a bug. The is by design. Since f has no variables it > is no longer > implicitly callable: > > sage: f.variables() > () > sage: f(1) > .ValueError: the number of arguments must be less than or equal to 0 > > You will have to instead write: > sage: f(t) = t*sin(0) > sage: f(1) > 0 > > or use > > sage: f=t*sin(0) > sage: f(t=0) > 0 > > This change was introduced because people often do the following > by accident: > > sage: a = (sqrt(2) + 17)(x+2) > sage: a > sqrt(2) + 17 > > Of course, that the above doesn't give an error even in 2.9 is a > bug! At least in most cases it works: > > sage: (SR(2) + 3)(x) > <type 'exceptions.ValueError'>: the number of arguments must be less > than or equal to 0 > > Also, this is a bug: > > sage: a = (I*17+3*5)(x+2) > AttributeError: 'I_class' object has no attribute 'number_of_arguments' > > > I want to emphasize that allowing > > sage: a = (sqrt(2) + 17)(x+2) > > and having it return sqrt(2) + 17 is *very* confusing to > a lot of people. I witnessed this time after time after time > when teaching a high school workshop using Sage this > summer -- it was really striking how often this happened. > > I made trac #1554 about this: > http://trac.sagemath.org/sage_trac/ticket/1554 > > Joel -- thanks for your feedback, and please comment > on the remarks I make above! Maybe I'm just completely > wrong?! > > -- William > > > > > It seems the originally submitted patch by was has a doc-test testing this > > very > > thing, but the actual code in my newly upgraded 2.9 just has a bunch of > > doc-strings that look like: > > """ > > EXAMPLES: > > """ > > with no examples! > > > > I'm not sure what went on beyond that. > > > > -- > > Joel > > > > > > > > > > > -- > William Stein > Associate Professor of Mathematics > University of Washington > http://wstein.org > > > > -- John Cremona --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@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-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
