#12438 closed defect (fixed)
Definite integral should not depend on the dummy variable
Reported by: | novoselt | Owned by: | burcin |
---|---|---|---|
Priority: | major | Milestone: | sage-5.1 |
Component: | symbolics | Keywords: | sd40.5 |
Cc: | kcrisman, jason | Merged in: | sage-5.1.beta3 |
Authors: | Andrey Novoseltsev | Reviewers: | Karl-Dieter Crisman, Benjamin Jones, Douglas McNeil |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
Consider the following:
sage: f(x) = x; f x |--> x sage: integral(f, x) x |--> 1/2*x^2 sage: integral(f, x, 0, 1) x |--> 1/2
The last integral has not "happened" to be constant - it does not depend on x mathematically, so it should not depend on x in Sage.
Multivariate case:
sage: f(x, y) = x + y sage: f (x, y) |--> x + y sage: integral(f, x, 0, 1) (x, y) |--> y + 1/2 sage: _(3) y + 1/2
integral(...)
here should return a symbolic function that depends on y only, so that the last evaluation gives 7/2
(and there are no warning about unnamed evaluation - the order of variables is the same as for the original function with one variable dropped).
See discussion here: http://groups.google.com/group/sage-devel/browse_thread/thread/1309eeae0714be79
Attachments (1)
Change History (22)
comment:1 Changed 8 years ago by
- Cc kcrisman jason added
comment:2 Changed 8 years ago by
- Keywords sd40.5 added
comment:3 Changed 8 years ago by
After rereading the original thread, as discussed in person, I think that extracting all the (callable) variables from the original expression and then returning a callable function with all but one of them in the same order (is this easy to do?) should be doable and ok.
comment:4 Changed 8 years ago by
The offending lines are
if is_CallableSymbolicExpressionRing(self._parent): return self._parent(integral(ring.SR(self), *args, **kwds))
So if we start with at function depending on x and y, the result will also be a function depending on x and y.
The question is now in distinguishing definite and indefinite integrals, as they have to be treated differently.
comment:6 Changed 8 years ago by
First three hunks replace TABs with spaces - I thought they were gone from the library?..
comment:7 Changed 8 years ago by
- Reviewers set to Karl-Dieter Crisman
This looks pretty good. Running tests.
comment:8 follow-up: ↓ 10 Changed 8 years ago by
Just so it's recorded:
sage: f(x) = x sage: var("y") y sage: integral(f, y, 0, 3) ERROR: An unexpected error occurred while tokenizing input The following traceback may be corrupted or invalid The error message is: ('EOF in multi-line statement', (580, 0)) --------------------------------------------------------------------------- ValueError Traceback (most recent call last) /home/mcneil/sagedev/sage-5.1.beta0/devel/sage-hack/sage/<ipython console> in <module>() /home/mcneil/sagedev/sage-5.1.beta0/local/lib/python2.7/site-packages/sage/misc/functional.pyc in integral(x, *args, **kwds) 726 """ 727 if hasattr(x, 'integral'): --> 728 return x.integral(*args, **kwds) 729 else: 730 from sage.symbolic.ring import SR /home/mcneil/sagedev/sage-5.1.beta0/local/lib/python2.7/site-packages/sage/symbolic/expression.so in sage.symbolic.expression.Expression.integral (sage/symbolic/expression.cpp:33895)() ValueError: list.remove(x): x not in list
comment:9 Changed 8 years ago by
Reviewer patch fixes one doctest - should be able to apply even after fixing this.
comment:10 in reply to: ↑ 8 Changed 8 years ago by
Replying to dsm:
Just so it's recorded:
> sage: f(x) = x > sage: var("y")
But
sage: var('y') y sage: integral(x,y,0,3) 3*x
so it's only that branch which causes problems.
comment:11 Changed 8 years ago by
No more problems and extra doctests are added!
Apply only trac_12438_drop_variable_of_definite_integration.patch
comment:12 Changed 8 years ago by
Fixed "OUPUT" typo.
comment:13 follow-up: ↓ 16 Changed 8 years ago by
The most recent patch applies with fuzz to sage-5.0:
Hunk #3 succeeded at 653 with fuzz 1 (offset -11 lines).
but maybe it applies cleanly to 5.1.beta0. Relevant tests pass in sage/calculus
, sage/symbolic
, and sage/functions
. I'm running a patchbot instance on it for the complete test suite.
comment:14 Changed 8 years ago by
- Reviewers changed from Karl-Dieter Crisman to Karl-Dieter Crisman, Benjamin Jones
comment:15 Changed 8 years ago by
Bloody patchbot, I repeat:
Apply only trac_12438_drop_variable_of_definite_integration.patch
(And I am working on 5.1.beta0, so hopefully there will be no fuzz during merging.)
comment:16 in reply to: ↑ 13 Changed 8 years ago by
- Reviewers changed from Karl-Dieter Crisman, Benjamin Jones to Karl-Dieter Crisman, Benjamin Jones, Douglas McNeil
Replying to benjaminfjones:
The most recent patch applies with fuzz to sage-5.0:
Hunk #3 succeeded at 653 with fuzz 1 (offset -11 lines).but maybe it applies cleanly to 5.1.beta0.
Correct, it does.
So we're set to go?
comment:17 Changed 8 years ago by
- Status changed from needs_review to positive_review
The 5.1.beta0 patchbot says tests pass, so I think we're good here. Positive review.
comment:18 Changed 8 years ago by
- Dependencies set to #2607
#2607 was fixing the same TABs as this ticket, I've rebased this one on top of that one. No code was changed, so I'll leave it at positive review.
comment:19 Changed 8 years ago by
- Dependencies #2607 deleted
I've realized that since I've just removed conflicting hunks this patch has become independent of #2607.
comment:20 Changed 8 years ago by
- Merged in set to sage-5.1.beta3
- Resolution set to fixed
- Status changed from positive_review to closed
comment:21 Changed 8 years ago by
On a related note, Sage has gone the other way on limits.
$ Downloads/sage-4.8/sage ---------------------------------------------------------------------- | Sage Version 4.8, Release Date: 2012-01-20 | | Type notebook() for the GUI, and license() for information. | ---------------------------------------------------------------------- sage: f(x) = x^2 sage: limit(f,x=1) x |--> 1 sage: limit(f(x),x=1) 1 sage: Exiting Sage (CPU time 0m1.15s, Wall time 0m10.57s). $ Desktop/sage-4.4.4-mcbc/sage ---------------------------------------------------------------------- | Sage Version 4.4.4, Release Date: 2010-06-23 | | Type notebook() for the GUI, and license() for information. | ---------------------------------------------------------------------- Loading Sage library. Current Mercurial branch is: hackbranch sage: f(x) = x^2 sage: limit(f,x=1) 1 sage: limit(f(x),x=1) 1
This seems bad, so I've opened #13221 for that.
Working on it.