William Stein wrote: > On Wed, Jun 3, 2009 at 11:45 AM, Robert Bradshaw > <[email protected]> wrote: > > > > Currently symbolic variables are un-indexable. What would people > > think of having indexing create new subscripted variables?
> That's a pretty wild and crazy idea. Cool. Does any other math > software do that? For the record, Maxima treats subscripted variables somewhat the same as simple variables. (They should be the same but Maxima is less than entirely consistent ....) A subscripted variable x[0] is distinct from x_0 and x0. Subscripted variables are the same as unevaluated function-like expressions except that they have an extra flag which shows that it's a subscript instead of a function argument. I think it's useful to consider subscripted variables as a subset of functional expressions; after all a subscripted variable is function which maps its set of indices to whatever. > Are there any obvious gotcha's? I think of two general shortcomings of Maxima's scheme. One is that x[m] and x[n] have no known relation when m and n are different; there isn't any way to apply some property across all of the subscripted variables x[foo]. The other is that x[foo] could be any of several things --- could be a list element, a matrix row, an array element, a hash table element, as well as a subscripted variable. This multitude of interpretations of x[foo] can lead to confusion. FWIW Robert Dodier --~--~---------~--~----~------------~-------~--~----~ 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-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
