"depends" problem of variables with subscripts

Ways in which subsup  variables differ from the mathematical (possible):

The index names are part of the object and not separable, at least after the
object is created.
For example, if you create  subsup x n 3,  and subsequently change the value
of n, that has no effect on subsup x n 3.
You cannot differentiate with respect to n. 
If your intention is to have a sub/super script denote an order of
differentiation, or an iterative application of a function e.g.  F^(3)(x)
is F(F(F(x))),  then the semantics will not be obvious.

In answer to your particular question, x and x[1] generally can coexist
separately.
 Though if there is no evidence that you have in mind any array named x,
 and x is set to a list like x:[a,b,c],  then x[1] evaluates to a.

Mathematical notation conventions generally frown on what you suggest.  If
you have a need for both x and x[1],
 perhaps you should be using X or bold_X or Xi ...  as in
X=[x[1],x[2],x[3]].

If you use x[1], x[2] and x[3],  and that is all,  and you don't iterate as
for i:1 thru 3 do ....x[i]..., then you are probably much better off using
x1, x2, x3.  As for the fact that you might like the appearance of
subscripts, If that is the biggest problem you encounter using Maxima, that
would be GREAT.

There are lots of parts of the display that you have relatively little
control over. For example, getting terms to be ordered exactly the right
way,  a+b or b+a, is something quite simple..



RJF


> -----Original Message-----
> From: maxima-bounces at math.utexas.edu 
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Evan
> Sent: Monday, July 09, 2007 7:03 PM
> To: fateman at cs.berkeley.edu
> Cc: maxima at math.utexas.edu
> Subject: Re: [Maxima] "depends" problem of variables with subscripts
> 
> I know nothing of programming in lisp, so all I can do now is 
> requesting, sorry
> 
> the code works for displaying, but variables introduced in this way
> will have some different behaviors as usual variables. maybe some more
> hacks are needed. It's ok for me to wait for these features to be
> included in a new release.
> 
> another question, will it cause problems if I introduce x and x[1] at
> the same time in derivations as independent variables, for x is
> actually the array name of the element x[1]?
> 
> On 7/10/07, Richard Fateman <fateman at cs.berkeley.edu> wrote:
> > See http://www.cs.berkeley.edu/~fateman/temp/subsuper.lisp
> >
> > For a solution to this problem using nformat.
> > It could be installed by you, or by one of the CVS owners.
> >
> > It makes atoms of the form subsup x 1 2    display with sub 
> and super
> > scripts.
> > It also shows how to make them.
> >
> > RJF
> >
> >
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