Opened 15 months ago
Last modified 4 weeks ago
#28207 new defect
Derivative of piecewise function returns junk
Reported by: | rburing | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-9.3 |
Component: | symbolics | Keywords: | piecewise, derivative, diff |
Cc: | Merged in: | ||
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
Reported in Ask SageMath question #47169, we can't differentiate the bump function:
sage: f(x) = piecewise([((-oo, -1), 0), ((-1, 1), exp(-1/(1 - x^2))), ((1, oo), 0)]) sage: f.diff() x |--> (0, 0, 0)*D[0]piecewise(x|-->0 on (-oo, -1), x|-->e^(1/(x^2 - 1)) on (-1, 1), x|-->0 on (1, +oo); x) + D[1]piecewise(x|-->0 on (-oo, -1), x|-->e^(1/(x^2 - 1)) on (-1, 1), x|-->0 on (1, +oo); x) sage: f.diff()(0) (0, 0, 0)*e^(-1) + e^(-1) sage: f.diff()(0) in RR False
That's not right...
Change History (3)
comment:1 Changed 9 months ago by
- Milestone changed from sage-8.9 to sage-9.1
comment:2 Changed 6 months ago by
- Milestone changed from sage-9.1 to sage-9.2
Batch modifying tickets that will likely not be ready for 9.1, based on a review of the ticket title, branch/review status, and last modification date.
comment:3 Changed 4 weeks ago by
- Milestone changed from sage-9.2 to sage-9.3
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