# [Maxima] symbolic subscript of literal list or matrix

Robert Dodier robert.dodier at gmail.com
Tue Jul 24 13:40:43 CDT 2007

```On 7/21/07, Stavros Macrakis <macrakis at alum.mit.edu> wrote:

> On 7/21/07, Robert Dodier <robert.dodier at gmail.com> wrote:
> > At present Maxima complains if the subscript of a literal list or matrix
> > is not an integer. E.g. a : [1, 2, 3]; a[k] => error.
> >
> > I would like to change it so that a subscript expression is returned.
> > E.g. a : [1, 2, 3]; a[k] => a[k]
>
> Why not [1,2,3][k]?  I assume we are talking about evaluation here, not just
> simplification (in which case the value of a would be irrelevant).

[1, 2, 3][k] is OK by me, although it is a little clumsier.

> > b : matrix([1, 2], [x, y]); b[j, k] => b[j, k]
>
> Why not matrix([1,2],[x,y])[j,k]?
>
> Similarly, matrix([1,2],[3,4])[1,i] should be [1,2][i] and
> matrix([1,2],[3,4])[i,1] should be [1,3][i].  If you want to get fancy,
> matrix([1,2],[3,4])[i,i] could simplify to [1,4][i]....

Yes, these alternatives are OK too.

Robert
```