Opened 3 years ago

Last modified 7 days ago

#27998 new defect

Solving a single equation for multiple variables doesn't work with assumptions

Reported by: Ricardo Buring Owned by:
Priority: major Milestone: sage-9.8
Component: symbolics Keywords: solve, assumptions, domain
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description

As reported in Ask SageMath question #46915:

sage: x,y = var('x,y', domain=RR)
sage: solve(x == 0, x, y)

gives an error message (unlike variants without assumptions, solving for a single variable, or adding a dummy equation).

It can be traced as follows: in sage/symbolic/relation.py the function solve calls _solve_expression to handle the single expression case. This (by default) uses the Maxima interface to create an initial list of solutions X, which is then filtered according to assumptions(). This filtering assumes that each solution in X is a single equation (it calls .lhs() on elements of X), which is not true in the case of multiple variables.

Change History (9)

comment:1 Changed 3 years ago by Erik Bray

Milestone: sage-8.8sage-8.9

Moving open critical and blocker issues to the next release milestone (optimistically).

comment:2 Changed 3 years ago by Erik Bray

Milestone: sage-8.9sage-9.1

Ticket retargeted after milestone closed

comment:3 Changed 2 years ago by Matthias Köppe

Milestone: sage-9.1sage-9.2

Moving tickets to milestone sage-9.2 based on a review of last modification date, branch status, and severity.

comment:4 Changed 2 years ago by Matthias Köppe

Milestone: sage-9.2sage-9.3

comment:5 Changed 17 months ago by Matthias Köppe

Milestone: sage-9.3sage-9.4

Moving to 9.4, as 9.3 has been released.

comment:6 Changed 13 months ago by Matthias Köppe

Milestone: sage-9.4sage-9.5

comment:7 Changed 9 months ago by Matthias Köppe

Milestone: sage-9.5sage-9.6

comment:8 Changed 5 months ago by Matthias Köppe

Milestone: sage-9.6sage-9.7

comment:9 Changed 7 days ago by Matthias Köppe

Milestone: sage-9.7sage-9.8
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