Earlier I typo'ed, I meant sign(zi - vi - ni*ci) should clearly be "nz"
On Tue, Apr 2, 2013 at 4:09 PM, Mike Valenzuela <mickle.mouse at gmail.com>wrote:
> Hello,
>
> I am attempting to determine the sign of an expression, but I have
> discovered that sign fails to solve even simpler problems than I am working
> on.
>
> %i1) assume(zi <= vi+ni*ci, zi>=0, vi>=0, ni>=0, ci>=0)$
> %i2) sign(zi - vi - ni*ci);
> %o2) pnz
>
> In my mind the answer seems to clearly be pz.
> Following from:
> zi <= vi+ni*ci
> zi -(vi+ni*ci) <= 0
> zi -vi - ni*ci <= 0
>
> I'm not sure if there is another package I have to include or what other
> assumptions are needed. Maybe the sign function is incomplete? Maybe
> inequalities are harder for Maxima to work with than equations?
>
> BTW, I'm using maxima version 5.28.0-2.
>
>