Re: [Maxima-discuss] Dependencies and constantness

[David S. <d.s...@go...>]

One problem is that many Maxima functions quote some arguments. For
example, when you define this:

setdepends_const(var) := (declare(var,constant), remove(var,dependency))$

"declare" and "remove" will always use the variable named "var" and not the
variable that you passed to your function. You have to use "apply":

apply(declare, [var, constant])
apply(remove, [var, dependency])

There are many other functions that do this. The manual should tell you.

Best regards
David Scherfgen


Eduardo Ochs <edu...@gm...> schrieb am Fr., 6. Juni 2025, 17:40:

> Hi list,
>
> the dependencies and the constantness of a variable seem to be stored
> in two places - in "dependencies" and in properties(var). We can check
> that with:
>
>                          [properties(a), diff(a)];
>   declare(a,constant)$   [properties(a), diff(a)];
>   remove (a,constant)$   [properties(a), diff(a)];
>                          [dependencies,  diff(a)];
>   depends(a,[x,y])$      [dependencies,  diff(a)];
>   remove (a,dependency)$ [dependencies,  diff(a)];
>
> I tried to write a function "setdepends" that would work like this,
>
>   setdepends(a,[])    - would declare a as constant
>   setdepends(a,[a])   - would set a in the default way, with diff(a)=del(a)
>   setdepends(a,[x,y]) - would work like depends(a,[x,y])
>
> I tried to write it as:
>
>   setdepends_const(var)      := (declare(var,constant),
> remove(var,dependency))$
>   setdepends_none (var)      := (remove (var,constant),
> remove(var,dependency))$
>   setdepends_other(var,deps) := (remove (var,constant), depends(var,deps))$
>   setdepends      (var,deps) :=
>     if     equal(deps,[])    then setdepends_const(var)
>     elseif equal(deps,[var]) then setdepends_none (var)
>     else                          setdepends_other(var,deps)$
>
>   setdepends(a,[])$    diff(a);   /* should yield 0 */
>   setdepends(a,[a])$   diff(a);   /* should yield del(a) */
>   setdepends(a,[x,y])$ diff(a);   /* should yield a_x del(x) + a_y del(y)
> */
>
> ...but my code has lots of errors, and I'm finding it hard to debug. =(
> Any suggestions?
>
>   Thanks in advance,
>     Eduardo Ochs
>     http://anggtwu.net/eev-maxima.html
>
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