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A Clone of Maxima's repo
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Maxima doesn't know much about increasing / decreasing fcns #483

Open rtoy opened 2 months ago

rtoy commented 2 months ago

Imported from SourceForge on 2024-07-02 23:22:03 Created by robert_dodier on 2006-05-07 02:15:00 Original: https://sourceforge.net/p/maxima/bugs/918

Maxima can't do much w/ functions declared to be increasing, and can't do anything with functions declared decreasing.

declare (F, increasing, G, decreasing); is (F(2) > F(1)); => "unable to evaluate the predicate" is (G(1) > G(2)); => "unable to evaluate the predicate" assume (xx > yy); is (F(xx) > F(yy)); => true (OK) is (G(yy) > G(xx)); => "unable to evaluate the predicate"

Maxima 5.9.3cvs

rtoy commented 2 months ago

Imported from SourceForge on 2024-07-02 23:22:05 Created by robert_dodier on 2016-06-24 04:11:42 Original: https://sourceforge.net/p/maxima/bugs/918/#6af1

Same behavior observed in current circa 5.38 Maxima. Curiously, I notice that with subscripted expressions, it works as expected:

(%i66) declare (F, increasing, G, decreasing);
(%o66)                               done
(%i67) is (F[2] > F[1]);
(%o67)                               true
(%i68) is (G[1] > G[2]);
(%o68)                               true
(%i69) assume (xx > yy);
(%o69)                             [xx > yy]
(%i70) is (F[xx] > F[yy]);
(%o70)                               true
(%i71) is (G[yy] > G[xx]);
(%o71)                               true