Re: [Maxima-discuss] How do I translate "(map 'list f as)" to Maxima?

[Eduardo O. <edu...@gm...>]

Hi all, esp. Barton,

ouch, it seems that my mental model of how "map" worked was wrong...
some of the strange recursions that I was complaining about are due to
listarith:true, not to map! And I lost the code in which I was trying
to use map for some complex list jugglings and something didn't
work...

Anyway, thanks a lot, and sorry for the noise!
  Cheers,
    Eduardo

On Tue, 24 Oct 2023 at 10:42, Barton Willis <wi...@un...> wrote:

>
> If you have found a bug in map, please report it.   Also, try doing* listarith
> : false *and rerunning your examples.
>
> --Barton
> ------------------------------
> *From:* Eduardo Ochs <edu...@gm...>
> *Sent:* Tuesday, October 24, 2023 08:30
> *To:* Michel Talon <ta...@lp...>
> *Cc:* max...@li... <
> max...@li...>
> *Subject:* Re: [Maxima-discuss] How do I translate "(map 'list f as)" to
> Maxima?
>
> Non-NU Email
> ------------------------------
> Hi Michel,
> map sometimes recurses on trees, not on lists:
>
>   f : lambda([x], x+10);
>   g : lambda([ab], 10*ab[1]+ab[2]);
>   f([3,4]);
>   map(f, [[1,2],[3,4],[5,6]]);  /* [[11, 12], [13, 14], [15, 16]] */
>   map(g, [[1,2],[3,4],[5,6]]);  /* [12, 34, 56] */
>   map(f, [[1,2],[3,4],5]);      /* [[11, 12], [13, 14], 15] */
>   map(g, [[1,2],[3,4],5]);      /* error */
>
> It tries to do the right thing and it usually does, but there are some
> cases in which its dtrt-iness is not what I expected... so I thought
> that it would be nice to also have some functions with a simpler
> logic.
>   Cheers,
>     Eduardo
>
>
> On Tue, 24 Oct 2023 at 05:48, Michel Talon <ta...@lp...> wrote:
>
> What is the problem with the simpler:
>
> (%i1) map(lambda([x],x+a),[2,3,4]);
> (%o1)                        [a + 2, a + 3, a + 4]
> (%i2) x:5;
> (%o2)                                  5
> (%i3) map(lambda([x],x+a),[2,3,4]);
> (%o3)                        [a + 2, a + 3, a + 4]
> (%i4) a:3;
> (%o4)                                  3
> (%i5) map(lambda([x],x+a),[2,3,4]);
> (%o5)                              [5, 6, 7]
>
> Le 24/10/2023 à 01:24, Eduardo Ochs a écrit :
>
> Hi list,
>
> what is the right/recommended way to define something like Lisp's
> "map" in Maxima? I tried this,
>
> to_lisp();
>   (defun foo (x) (* x 10))
>   (map 'list 'foo '(2 3 5 8))             ;;-> (20 30 50 80)
>   (to-maxima)
>
> map_list(f, as) := makelist(apply(f, [a]), a, as);
> map_list(lambda([x], 10*x), [2, 3, 5, 8]);  /* [20, 30, 50, 80]     */
> map_list(lambda([x], x+b),  [2, 3, 5, 8]);  /* [b+2, b+3, b+5, b+8] */
> map_list(lambda([x], x+a),  [2, 3, 5, 8]);  /* [4, 6, 10, 16]       */
>
> but it doesn't work well in cases like the last one, in which f
> mentions a global variable with the same name as the variable used in
> the makelist...
>
> Thanks in advance!
>   Cheers =),
>     Eduardo Ochs
>
>
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> --
> Michel Talon
>
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