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**[bugs:#4639] dim-%antideriv: a partial fix for a bug in widths**
**Status:** open
**Group:** None
**Created:** Sun Nov 30, 2025 01:38 AM UTC by Eduardo Ochs
**Last Updated:** Sun Nov 30, 2025 01:38 AM UTC
**Owner:** nobody
**Attachments:**
- [with-setq-width.png](https://sourceforge.net/p/maxima/bugs/4639/attachment/with-setq-width.png) (25.7 kB; image/png)
- [without-setq-width.png](https://sourceforge.net/p/maxima/bugs/4639/attachment/without-setq-width.png) (25.8 kB; image/png)
These are the messages M1 and M2, about "dim-%antideriv":
M1: <https://sourceforge.net/p/maxima/mailman/message/59178281/>
M2: <https://sourceforge.net/p/maxima/mailman/message/59266596/>
M1 is by Robert Dodier, in which he sent the code for
"dim-%antideriv", and M2 is by me, in which I showed that by adding
one line to Robert's code we can make it calculate the width correctly
in most - but not all - cases.
Robert asked me to send the code and the screenshots to the bug
tracker, so here it goes. The code is below, with the "setq" that I
added marked with ";; Edrx:", and with my tests in the comments at the
end. The screenshot named "without-setq-width.png" shows that the
widths were incorrect in all the four tests - o1, o2, o3, and o4 - and
the screenshot named "with-setq-width.png" shows that after my fix the
tests o1, o2, and o4 are good, but the width in o3 still has a one-off
error.
--snip--snip--
~~~
(if (not (fboundp 'display2d-unicode-enabled))
(defun display2d-unicode-enabled () nil))
(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 $absboxchar 'list))))
vertical-bar
expr-result
lower-result
upper-result
expr-w expr-h expr-d
lower-w lower-h lower-d
upper-w upper-h upper-d)
(declare (ignorable expr-w expr-h expr-d
lower-w lower-h lower-d
upper-w upper-h upper-d))
(setq expr-result (dimension expr nil 'mparen 'mparen nil 0)
expr-w width
expr-h height
expr-d depth)
(setq lower-result (dimension-infix lower-eqn nil)
lower-w width
lower-h height
lower-d depth)
(setq upper-result (dimension-infix upper-eqn nil)
upper-w width
upper-h height
upper-d depth)
(setq vertical-bar (list 'd-vbar
(1+ (max expr-h upper-d))
(max (1+ expr-d) lower-h)
vertical-bar-char))
(setq result (append (list (append (list (- lower-w) (max expr-h upper-d)) upper-result)
(append (list 0 (- (max (1+ expr-d) lower-h))) lower-result)
vertical-bar
(append (list 0 0) expr-result))
result))
(setq height (+ 1 (max expr-h upper-d) upper-h)
depth (+ (max (1+ expr-d) lower-h) lower-d))
;; Edrx:
(setq width (+ expr-w 1 (max upper-w lower-w)))
(update-heights height depth)
result))
(setf (get '%antideriv 'dimension) 'dim-%antideriv)
(setf (get '$antideriv 'dimension) 'dim-%antideriv) ; Edrx
#|
• (eepitch-maxima)
• (eepitch-kill)
• (eepitch-maxima)
load ("dim-antideriv.lisp");
mybox(o) := [box(o)];
o1 : antideriv (F(u), u, a, b);
o2 : antideriv (F(u[k]), u[k], a[k], b[k]);
o3 : antideriv (a+b, u, z^2^n+y[k], x^2-z[k]);
o4 : antideriv (a+b, u, z^2^n+y[k], x^2-z[k[l[u]]]);
mybox(o1);
mybox(o2);
mybox(o3);
mybox(o4);
|#
~~~
--snip--snip--
Cheers,
Eduardo Ochs
https://anggtwu.net/eev-maxima.html
http://anggtwu.net/MAXIMA/dim-antideriv.lisp.html
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