Opened 7 years ago
Closed 9 months ago
#15496 closed defect (fixed)
Incorrect result for divergent integral
Reported by: | ppurka | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-9.2 |
Component: | calculus | Keywords: | |
Cc: | kcrisman, jakobkroeker, slelievre, vklein, rws, tscrim | Merged in: | |
Authors: | Frédéric Chapoton | Reviewers: | Travis Scrimshaw |
Report Upstream: | N/A | Work issues: | |
Branch: | u/chapoton/15496 | Commit: | 0661926ece85d45ed1018fa9d508dfcf7bb90add |
Dependencies: | Stopgaps: |
Description (last modified by )
From google spreadsheet which no one reads X-(
sage: integrate(x^2/exp(-1/(x^2+1))/(x^2+1),(x,-infinity,infinity)).n() -3.3357920860949157
Wolfram alpha gives the correct answer.
The problem comes from here:
sage: D=1.00000000000000*x^2*e^(1/(x^2 + 1.00000000000000))/(x^2 + 1.00000000000 ....: 000) sage: numerical_integral(D,-oo,+oo) (-3.3357920860949157, 4.262178610048295e-09)
and in one specific algorithm
sage: numerical_integral(D,-oo,+oo, algorithm="qag") (-3.3357920860949157, 4.262178610048295e-09) sage: numerical_integral(D,-oo,+oo, algorithm="qng") (nan, nan) sage: numerical_integral(D,-oo,+oo, algorithm="qags") (nan, nan)
and this case is handled by
gsl_integration_qagi
And the problem can be cut into two parts:
sage: numerical_integral(D,0,+oo) (-1.6678960430474579, 2.1310893050241475e-09) sage: numerical_integral(D,-oo,0) (-1.6678960430474579, 2.1310893050241475e-09)
Change History (16)
comment:1 Changed 7 years ago by
- Cc kcrisman added
comment:2 Changed 7 years ago by
- Milestone changed from sage-6.1 to sage-6.2
comment:3 Changed 7 years ago by
- Milestone changed from sage-6.2 to sage-6.3
comment:4 Changed 7 years ago by
- Milestone changed from sage-6.3 to sage-6.4
comment:5 Changed 4 years ago by
- Cc jakobkroeker added
comment:6 Changed 10 months ago by
- Description modified (diff)
comment:7 Changed 10 months ago by
- Description modified (diff)
comment:8 Changed 10 months ago by
- Description modified (diff)
comment:9 Changed 10 months ago by
- Description modified (diff)
comment:10 Changed 10 months ago by
- Branch set to u/chapoton/15496
- Commit set to 0661926ece85d45ed1018fa9d508dfcf7bb90add
- Status changed from new to needs_review
here is a proposal : check that the limit is zero before doing the numerical integral
New commits:
0661926 | add some safety check for numerical integrals up to infinity
|
comment:11 Changed 10 months ago by
- Milestone changed from sage-6.4 to sage-9.2
- Stopgaps todo deleted
comment:13 Changed 10 months ago by
- Cc vklein rws added
comment:14 Changed 10 months ago by
- Cc tscrim added
comment:15 Changed 10 months ago by
- Reviewers set to Travis Scrimshaw
- Status changed from needs_review to positive_review
LGTM.
comment:16 Changed 9 months ago by
- Resolution set to fixed
- Status changed from positive_review to closed
These have been merged into 9.2.beta4
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This is not a symbolic Maxima problem, as the integral is just returned, so it's something about how we evaluate
n
on these unevaluated integrals.