Opened 3 years ago
Closed 3 years ago
#20455 closed defect (invalid)
rewrite buggy Expression.coefficients() without Maxima
Reported by: | rws | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-duplicate/invalid/wontfix |
Component: | symbolics | Keywords: | |
Cc: | paulmasson | Merged in: | |
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
At the moment the ex1.coefficients(ex2)
method uses pexpect-Maxima to get a coefficient list of a symbolic expression ex1
when seen as a polynomial in ex2
but the list is wrong whenever the exponent of ex2
is nonnumeric:
sage: var('a, x') (a, x) sage: f = a*x - x^x sage: f.coefficient(x^x) -1 sage: f.coefficients(x) [[-x^x, 0], [a, 1]]
It should not be difficult to rewrite coefficients
using wildcard power search and the coefficient
method (which doesn't use Maxima).
Change History (6)
comment:1 Changed 3 years ago by
comment:2 Changed 3 years ago by
- Cc paulmasson added
comment:3 Changed 3 years ago by
This is fixed in current Pynac master.
comment:4 Changed 3 years ago by
- Milestone changed from sage-7.2 to sage-duplicate/invalid/wontfix
- Status changed from new to needs_review
Since #21369 contains doctests for this, it can be closed.
comment:5 Changed 3 years ago by
- Status changed from needs_review to positive_review
comment:6 Changed 3 years ago by
- Resolution set to invalid
- Status changed from positive_review to closed
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For implementation reasons the rewrite happened in #21034 but the behaviour was not changed so this ticket still has to be addressed.