#15906: solve should solve inequalities that are operated on
---------------------------+----------------------------
Reporter: rws | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-6.2
Component: symbolics | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies: #7660
Stopgaps: |
---------------------------+----------------------------
In #7660 inequalities will be handled differently, and e.g. multiplying
`x>1` with `-1` will yield `-(x>1)`. These formal expressions cannot be
solved because---after applying the patch in #7660 they are parsed as
arithmetic:
{{{
sage: solve(-(x > 1),x)
...
RuntimeError: ECL says: THROW: The catch MACSYMA-QUIT is undefined.
}}}
{{{
sage: solve_ineq((x>1)*(-1),[x,y])
#0: solve_rat_ineq(ineq=-(x > 1))
...
TypeError: ECL says: Error executing code in Maxima: solve_rat_ineq: -(x
> 1) is not an inequality.
}}}
Since, by definition, operations on both lhs and rhs do not change the
outcome, in one of the above two cases the outer op should be stripped
away and the result solved.
This ticket depends on #7660 having been implemented as proposed, as
without you couldn't doctest it.
--
Ticket URL: <http://trac.sagemath.org/ticket/15906>
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