Opened 8 years ago

Closed 7 years ago

#15906 closed enhancement (invalid)

solve should solve inequalities that are operated on

Reported by: rws Owned by:
Priority: minor Milestone: sage-duplicate/invalid/wontfix
Component: symbolics Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: #7660 Stopgaps:

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Description (last modified by rws)

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, simple 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.

Change History (7)

comment:1 Changed 8 years ago by rws

  • Description modified (diff)

comment:2 Changed 8 years ago by rws

  • Priority changed from major to minor

comment:3 Changed 8 years ago by vbraun_spam

  • Milestone changed from sage-6.2 to sage-6.3

comment:4 Changed 8 years ago by vbraun_spam

  • Milestone changed from sage-6.3 to sage-6.4

comment:5 Changed 7 years ago by rws

  • Milestone changed from sage-6.4 to sage-duplicate/invalid/wontfix
  • Status changed from new to needs_review

After the new much more sensible proposal of #7660 this ticket is no longer relevant.

comment:6 Changed 7 years ago by rws

  • Status changed from needs_review to positive_review

comment:7 Changed 7 years ago by vbraun

  • Resolution set to invalid
  • Status changed from positive_review to closed
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