Subject: symbolic subscript of literal list or matrix
From: Barton Willis
Date: Tue, 24 Jul 2007 14:04:34 -0500
Barton
-----"Robert Dodier" <robert.dodier at gmail.com> wrote: -----
>To: "Barton Willis" <willisb at unk.edu>
>From: "Robert Dodier" <robert.dodier at gmail.com>
>Date: 07/24/2007 01:51PM
>cc: "Stavros Macrakis" , maxima
><maxima at math.utexas.edu>
>Subject: Re: [Maxima] symbolic subscript of literal list or matrix
>
>On 7/24/07, Barton Willis <willisb at unk.edu> wrote:
>
>> >> > I would like to change it so that a subscript expression is
>returned.
>> >> > E.g. a : [1, 2, 3]; a[k] => a[k]
>>
>> What problem does this solve?
>
>I bumped into it in the following example, which I don't consider
>far-fetched.
>
>L : [1, 2, 3, 4, 5];
>'sum (L[k], k, 1, 5);
>=>
>Subscript must be an integer:
>g15913
Oh, I see. This seems like a reasonable thing to do. A
user could do:
(%i1) L : [1, 2, 3, 4, 5]$
(%i2) sum (L[k], k, 1, n);
Subscript must be an integer:
(%i3) '(sum (L[k], k, 1, n));
(%o3) sum(L[k],k,1,n)
(%i4) subst(n=5,%);
(%o4) sum(L[k],k,1,5)
(%i5) ev(%);
(%o5) 15
(%i6) '(sum (L[k], k, 1, 5));
(%o6) sum(L[k],k,1,5)
(%i7) ev(%,sum);
(%o7) 15
Barton