I seem to remember that Maple has a function "unapply" which when applied to a symbolic expression with one variable, returns a callable function, e.g. unapply(t*cos(0)) would return a callable function t -> t*cos(0). I cannot remember if it could handle symbolic expressions with more than one variable. Perhaps someone with access to Maple can answer that.
Is that something we might want to provide? John On 17/12/2007, Joel B. Mohler <[EMAIL PROTECTED]> wrote: > > On Monday 17 December 2007 11:41, William Stein wrote: > > 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 > > Ok, I agree that this is correct. And, furthermore, I think -- and have > thought for a long time -- that > sage: f=t*cos(0) > should also not create a callable function. The situation I ran into this was > > sage: parametric_plot( (t*cos(0),t*sin(0)), t=...) > It seems like a perfectly logical command in my script because the next line > is > sage: parametric_plot( (1*cos(t),1*sin(t)), t=...) > > Now, I'm perfectly fine with your solution to not make it callable, but I > think it is going to produce a collection of inconsistent results of this > nature. And, as I say, I think the correct solution is not to make any > symbolic solution arbitrarily callable unless it is explicitly promoted to > being callable in some way. > > But, as should be obvious, I did appreciate the sort of lazy call-ability > which I argued against in the previous paragraph. I admit its nice to use > even if it is ambiguous and error-prone. > > -- > Joel > > > > -- 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/ -~----------~----~----~----~------~----~------~--~---
