#7325: Sage cannot solve inequalities
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Reporter: robert.marik | Owner: tbd
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.3.1
Component: algebra | Keywords: relation, symbolics, inequality,
solve
Work_issues: | Author: Robert Marik
Upstream: N/A | Reviewer: Karl-Dieter Crisman
Merged: |
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Changes (by kcrisman):
* status: needs_review => needs_work
Comment:
I will hopefully soon have time to actually test this - thanks for your
patience! Here are a few things to keep in mind for when you rebase to
4.3.1.alpha1 (as #7745 is now merged).
0. Rebase, of course :)
1. I think I agree that x>-Infinity is much more "Sage-like", or maybe
{{{[x>-Infinity]}}} would be more in keeping with the other solutions.
Good thought. Or maybe {{{[x>-Infinity, x<Infinity]}}} ? I'm not sure
about that.
2. Probably {{{``special cases``}}} shouldn't be in the quoting
environment. In fact, [] and the above are both lists, so you would just
need to clarify what they mean.
3. Something similar should happen with multivariate. Here, there is also
a small inconsistency involved - {{{[0 < y, y < x, 0 < x]}}} for
multivariate, but {{{[[0 < y, y < x, 0 < x]]}}} seems to be the univariate
result type.
4. In calculus/calculus.py, there is the following code:
{{{
maxima = Maxima(init_code = ['display2d:false', 'domain: complex',
'keepfloat: true', 'load(to_poly_solver)', 'load(simplify_sum)'],
script_subdirectory=None)
}}}
Maybe the initialization of solve_rat_ineq and fourier_elim should be
there? Otherwise we are trying to load this with every attempt at a
solve_ineq, which seems inefficient.
5. Looking at things, I wonder if it would be possible (without too many
bugs) to actually implement ineq.solve(), not just solve(ineq) - that is,
in relation.py and expression.py, rather than having solve() gag on
inequalities, have it at least try the solve_ineq and just catch any
exceptions that are raised and instead raise a NotImplementedError for
that particular inequality. I wonder?
But as before, a great addition to Sage - just trying to get the maximum
benefit from this ticket! Thanks again.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7325#comment:19>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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