Opened 5 months ago
Last modified 5 weeks ago
#27314 new defect
Can't solve symbolic equations containing inexact (e.g. RIF, RBF) numbers
Reported by: | rburing | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | |
Component: | symbolics | Keywords: | RIF, RBF, solve |
Cc: | Merged in: | ||
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
There are (undocumented?) symbolic wrappers around RIF
, RBF
objects, but solving equations with them
sage: var('x') sage: solve(x + RIF(0.999,1.001) == 0, x)
fails because the inexact objects cannot be converted to Maxima objects.
This is confusing to new users; see Ask SageMath: long traceback when calling solve().
Specifying algorithm='sympy'
gives a solution but loses information about precision.
The least thing that could be done is for solve(eqn, x)
to check eqn.is_exact()
and give a warning.
Change History (3)
comment:1 Changed 5 months ago by
comment:2 Changed 4 months ago by
- Milestone changed from sage-8.7 to sage-8.8
Ticket retargeted after milestone closed (if you don't believe this ticket is appropriate for the Sage 8.8 release please retarget manually)
comment:3 Changed 5 weeks ago by
- Milestone sage-8.8 deleted
As the Sage-8.8 release milestone is pending, we should delete the sage-8.8 milestone for tickets that are not actively being worked on or that still require significant work to move forward. If you feel that this ticket should be included in the next Sage release at the soonest please set its milestone to the next release milestone (sage-8.9).
One notes that numerical root seeking via
find_root
also fails for both RIF and RBF :Extending
find_root
to handle RIF and RBF expressions would allow to handle the cases where no explicit form of a root solution is known (e. g. implicit expressions resulting ofsolve
), wherefind_root
allows to compute a numerical approxomation.This would certainly be handy (but is probably a significant project in itself !).
It might also be useful to check which of the optimization functions in Sage support such uncertainty handling...