[Maxima-bugs] [maxima:bugs] #3356 BUG: assume(a<=0,b<=0); sign(a*b);

[rk7 <rk...@us...>]

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** [bugs:#3356] BUG: assume(a<=0,b<=0);sign(a*b);**

**Status:** open
**Group:** None
**Created:** Tue Nov 14, 2017 03:14 PM UTC by rk7
**Last Updated:** Tue Nov 14, 2017 03:14 PM UTC
**Owner:** nobody


Hello

With Maxima 5.38.1 I get the following

(%i1) assume(a<=0,b<=0);sign(a*b);
(%o1)                          [a <= 0, b <= 0]
(%o2)                                 nz

I'd expect pz...



Stavros Macrakis added:

Please report this (serious!) bug at sourceforge.

Other, related, cases work correctly:

     assume(q<0,r<0)$

     sign(q*r) => pos
     sign(a*r) => pz
     sign(a*-2) => pz
     sign(a*q*r) => nz
 
BUT

     sign(a*b*q) => pz SHOULD BE nz

Thanks!


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