Re: [Maxima-discuss] Writing low-level `dim-*' functions

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

That's EXACTLY what I was looking for!...
And that code is much clearer than dim-%at and dim-$matrix...
Many many many thanks! =) =) =)
  Cheers,
    Eduardo =)

P.S.: I'm attaching a screenshot.


On Tue, 29 Apr 2025 at 03:26, Robert Dodier <rob...@gm...> wrote:

> Eduardo, I'm not sure if you've already solved this problem, but if not,
> maybe this is helpful.
>
> Here's a display for the way antiderivatives are often evaluated in
> elementary calculus classes. I'm guessing that's why you were looking at
> at-like expressions.
>
> (%i2) load ("dim-antideriv.lisp");
> (%o2)                  dim-antideriv.lisp
> (%i3) 'antideriv (F(u), u, a, b);
>                                   │u = b
> (%o3)                         F(u)│
>                                   │u = a
> (%i4) 'antideriv (F(u[k]), u[k], a[k], b[k]);
>                                   │u  = b
> (%o4)                        F(u )│ k    k
>                                 k │
>                                   │u  = a
>                                     k    k
> (%i5) 'antideriv(a+b,u,z^2^n+y[k],x^2-z[k]);
>                                       2
>                                 │u = x  - z
> (%o5)                      b + a│          k
>                                 │      n
>                                 │     2
>                                 │u = z   + y
>                                             k
> (%i6) 'antideriv(a+b,u,z^2^n+y[k],x^2-z[k[l[u]]]);
>                                      2
>                                │u = x  - z
>                                │          k
>                                │           l
> (%o6)                     b + a│            u
>                                │      n
>                                │     2
>                                │u = z   + y
>                                            k
>
> The code shown in the PS is adapted from DIM-%AT with some modifications.
> I tried to make it clearer but it is still fairly obtuse. The tricky part
> was getting the subexpressions to line up correctly ... it took quite a
> number of tries to get it all straightened out.
>
> Hope this helps, if not I'll give it another try.
>
> Robert
>
> PS.
>
> ;; DIM-%ANTIDERIV -- 2-d pretty printer display for antiderivative-like
> expressions
> ;; copyright 2025 by Robert Dodier
> ;; I release this work under terms of the GNU General Public License, v2
>
> (defun dim-%antideriv (form result)
>
>   (unless (= (length (cdr form)) 4)
>     (return-from dim-%antideriv (dimension-function form result)))
>
>   (let*
>     ((args (rest form))
>      (expr (first args))
>      (my-var (second args))
>      (lower-val (third args))
>      (upper-val (fourth args))
>      (lower-eqn (list '(mequal) my-var lower-val))
>      (upper-eqn (list '(mequal) my-var upper-val))
>      (vertical-bar-char (if (display2d-unicode-enabled) at-char-unicode
> (car (coerce $absboxchar 'list))))
>      vertical-bar
>      expr-result lower-result upper-result
>      expr-w expr-h expr-d lower-w lower-h lower-d upper-w upper-h upper-d)
>     (declare (ignorable expr-w expr-h expr-d lower-w lower-h lower-d
> upper-w upper-h upper-d))
>
>     (setq expr-result (dimension expr nil 'mparen 'mparen nil 0)
>           expr-w width expr-h height expr-d depth)
>
>     (setq lower-result (dimension-infix lower-eqn nil)
>           lower-w width lower-h height lower-d depth)
>
>     (setq upper-result (dimension-infix upper-eqn nil)
>           upper-w width upper-h height upper-d depth)
>
>     (setq vertical-bar (list 'd-vbar (1+ (max expr-h upper-d)) (max (1+
> expr-d) lower-h) vertical-bar-char))
>
>     (setq result (append (list (append (list (- lower-w) (max expr-h
> upper-d)) upper-result)
>                                (append (list 0 (- (max (1+ expr-d)
> lower-h))) lower-result)
>                                vertical-bar
>                                (append (list 0 0) expr-result))
>                          result))
>
>     (setq height (+ 1 (max expr-h upper-d) upper-h)
>           depth (+ (max (1+ expr-d) lower-h) lower-d))
>
>     (update-heights height depth)
>
>     result))
>
> (setf (get '%antideriv 'dimension) 'dim-%antideriv)
>
>