What exactly is that status of the old and new assumptions systems in
sympy? I've read a few things including
https://github.com/sympy/sympy/wiki/Assumptions but I'm still a little
confused.
Are the two systems properly independent of one another? When I use
Symbol('x', positive=True) will that positive flag be ignored when
using ask(x,...)? Actually I think I can answer that question myself:
(using master)
>>> from sympy import *
>>> x = Symbol('x', positive=True)
>>> y = Symbol('y')
>>> simplify(abs(x))
x
>>> refine(abs(x))
x
>>> simplify(abs(y))
Abs(y)
>>> refine(abs(y))
Abs(y)
>>> ask(Q.positive(x))
True
>>> ask(Q.positive(x), Q.negative(x))
True
>>> ask(Q.positive(y), Q.negative(y))
False
>>> print(ask(Q.positive(y)))
None
So it seems that the new system uses the positive attribute on x even
if it contradicts the explicit assumptions passed to ask. Presumably
then as a user I need to be disciplined in not using both systems.
Should I future-proof my own code by sticking to the new system?
But what are the plans for this in future? It seems that sympy is
about to release version 1.0 but isn't this exactly the kind of thing
that would normally be resolved before a 1.0 release?
This isn't a criticism: I'm just trying to understand where sympy's going.
--
Oscar
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