[Maxima-discuss] use of subscripts, was: Yamwi (was: Construct sequence of identifiers)

[Robert D. <rob...@gm...>]

On Sat, Jul 22, 2023 at 12:38 AM Wolfgang Hugemann <Au...@hu...> wrote:

> Thanks for that hint. But in engineering subscripts are not always meant
> as a variable index, but often serve as a means to distinguish quantities.
>
> If you denote the drag coefficient as c_d
> (https://en.wikipedia.org/wiki/Drag_(physics)), you surely don't mean
> c[d].

Well, Maxima doesn't require subscripts to correspond to indices; instead a
more general correspondence is allowed. In fact, subscripts can be any
expressions, and there is no requirement that they form a complete set of
anything. (Internally values assigned to subscripted variables are stored
in a hash table.) In that sense, the subscript does indeed just serve as an
indicator to distinguish conceptually-related quantities.

Also of interest in this context, a recently-added feature (present in
Maxima 5.44 and later) is that one can declare subscripts to be displayed
above or below, before or after the base symbol. See
declare_index_properties. E.g.:

(%i11) declare_index_properties (FOO, [presubscript, presuperscript,
postsuperscript, postsubscript]);
(%o11)                        done
(%i12) FOO[a, b, c, d];
                              b   c
(%o12)                         FOO
                              a   d


All the best,

Robert

PS. I see now that the function is misnamed; it should be called
declare_subscript_properties. See, I got myself mixed up ... oh well!