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Spurious solution using arc-trig #430

Open rtoy opened 1 week ago

rtoy commented 1 week ago

Imported from SourceForge on 2024-07-02 19:49:20 Created by kcrisman on 2014-06-30 14:09:23 Original: https://sourceforge.net/p/maxima/bugs/2773

Wrong solution. Maxima even knows this solution is wrong and computes the limit correctly elsewhere.

Maxima 5.33.0 http://maxima.sourceforge.net
using Lisp ECL 12.12.1
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) solve(sin(cos(x))/cos(x) = 0, x);

solve: using arc-trig functions to get a solution.
Some solutions will be lost.
                                        %pi
(%o1)                              [x = ---]
                                         2
(%i2) limit(sin(cos(x))/cos(x),x,%pi/2);
(%o2)                                  1
rtoy commented 1 week ago

Imported from SourceForge on 2024-07-02 19:49:21 Created by kcrisman on 2014-06-30 14:10:49 Original: https://sourceforge.net/p/maxima/bugs/2773/#d7b1

This is also reported downstream at http://trac.sagemath.org/ticket/16593