Opened 5 years ago
Last modified 7 months ago
#8728 needs_work defect
doctest fixed integral from Maxima
Reported by: | kcrisman | Owned by: | burcin |
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Priority: | major | Milestone: | sage-6.4 |
Component: | calculus | Keywords: | |
Cc: | Merged in: | ||
Authors: | Ralf Stephan | Reviewers: | |
Report Upstream: | Fixed upstream, in a later stable release. | Work issues: | |
Branch: | u/rws/doctest_fixed_integral_from_maxima (Commits) | Commit: | fab73690cd00e86c063be62e578a502267e7db94 |
Dependencies: | Stopgaps: |
Description (last modified by rws)
This is fixed now and needs a doctest:
From #sage-devel:
Boulemans left the chat room. (Read error: Connection reset by peer) [11:58am] Boule joined the chat room. [11:58am] Boule: (laptop shutdown due to power supply) [11:59am] Boule: e, T, w = var("e T w"); assume(1 = e^2)>0; integrate(cos(w+T)/(1+e*cos(T))^2,T,0,2*pi) should give -2*pi e cos w/(1-e^2)^3/2 instead of 0 [11:59am] Boule: can someone help? [12:00pm] wjp: yeah, sage seems to have some trouble with this integral. You could try http://groups.google.com/group/sage-support since the right people don't seem to be here currently [12:00pm] Boule: ok, thanx [12:08pm] kcrisman: By the way, I just tried this and get a hang in Maxima. Can you type the exact commands which lead to an answer of 0? [12:08pm] kcrisman: If I plug something (.5, .75) in for e in Maxima in Sage, I do get zero as an output. [12:12pm] Boule: don't know maxima, but with numerical values for e and w at wolfram-alfa, it gives something different than 0 [12:13pm] wjp: *nod* maple gives non-zeros too [12:13pm] kcrisman: Can you give the *exact* sequence of commands which yield zero in Sage itself? [12:14pm] Boule: e = var('e') [12:14pm] Boule: T = var('T') [12:14pm] Boule: w = var('w') [12:14pm] baali1 joined the chat room. [12:14pm] baali left the chat room. (Quit: Leaving.) [12:15pm] Boule: assume(1-e^2>0) [12:15pm] Boule: integrate(cos(w+T)/(1+e*cos(T))^2,T,0,2*pi) [12:15pm] kcrisman: Okay, that's what I thought. [12:16pm] kcrisman: Okay, it takes a while but I do get 0.
Change History (22)
comment:1 follow-up: ↓ 6 Changed 5 years ago by jason
comment:2 Changed 5 years ago by jason
#8729 may point to a solution.
comment:3 Changed 5 years ago by kcrisman
Hmm, I forgot about this, and it's true it never got implemented, did it?
comment:4 Changed 5 years ago by jason
It was fixed about two weeks ago in maxima. There was a new release of maxima a few days ago---I'm trying to make an spkg right now.
comment:5 Changed 5 years ago by kcrisman
Sweet. I haven't been keeping up on the Maxima list lately, thanks.
comment:6 in reply to: ↑ 1 Changed 5 years ago by jason
Replying to jason:
I wonder if this is another manifestation of this bug:
sage: integrate(sqrt(sin(x)^2+cos(x)^2), x,0,2*pi) pi
I just checked; this ticket isn't the same bug.
comment:7 Changed 5 years ago by jason
The upgrade to maxima 5.21.1 does not fix this. After #8731:
sage: e, T, w = var("e T w") sage: assume(1-e^2>0) sage: integrate(cos(w+T)/(1+e*cos(T))^2,T,0,2*pi) 0
comment:8 Changed 4 years ago by kcrisman
Maxima 5.23.2 still has this, and we still haven't reported it.
Maxima 5.23.2 http://maxima.sourceforge.net using Lisp SBCL 1.0.24 Distributed under the GNU Public License. See the file COPYING. Dedicated to the memory of William Schelter. The function bug_report() provides bug reporting information. (%i1) assume(1-e^2>0); 2 (%o1) [e < 1] (%i3) integrate(cos(w+T)/(1+e*cos(T))^2,T,0,2*%pi); (%o3) 0
This is now Maxima bug 3211975.
comment:9 Changed 4 years ago by kcrisman
- Report Upstream changed from Not yet reported upstream; Will do shortly. to Fixed upstream, but not in a stable release.
According to the bug report, this is now fixed. However, some examples may still throw a Lisp error, so we should check out whether that will affect us before saying we're totally fixed when we upgrade.
comment:10 Changed 3 years ago by kcrisman
Maxima 5.28 is now out.
comment:11 Changed 3 years ago by kcrisman
See #13973 where this should (?) be fixed, just need a doctest here?
comment:12 Changed 2 years ago by jdemeyer
- Milestone changed from sage-5.11 to sage-5.12
comment:13 Changed 19 months ago by vbraun_spam
- Milestone changed from sage-6.1 to sage-6.2
comment:14 Changed 16 months ago by vbraun_spam
- Milestone changed from sage-6.2 to sage-6.3
comment:15 follow-up: ↓ 17 Changed 16 months ago by pbruin
In Maxima 5.33.0 (see #13973):
(%i1) assume(e^2<1); 2 (%o1) [e < 1] (%i2) integrate(cos(w+T)/(1+e*cos(T))^2, T, 0, 2*%pi); 2 Is abs(e) - sqrt(1 - e ) - 1 positive, negative or zero? negative; ! 2 ! Is !sqrt(1 - e ) - 1! - abs(e) positive, negative or zero? negative; 2 2 %pi e sqrt(1 - e ) cos(w) (%o2) - --------------------------- 4 2 e - 2 e + 1
This appears to be the correct answer. Note that the answers to both questions are "negative" for all e with -1 < e < 1, so it would be nice if Maxima didn't ask those questions.
comment:16 Changed 13 months ago by vbraun_spam
- Milestone changed from sage-6.3 to sage-6.4
comment:17 in reply to: ↑ 15 Changed 11 months ago by kcrisman
In Maxima 5.33.0 (see #13973):
This appears to be the correct answer. Note that the answers to both questions are "negative" for all e with -1 < e < 1, so it would be nice if Maxima didn't ask those questions.
The thing noted in the message upstream when they closed their ticket
sage: integrate(cos(w+T)/(1+.5*cos(T))^2,T,0,2*pi) <boom>
does still happen, but I think that is a different issue tracked elsewhere here (the usual keepfloat thing).
So... do we have a reasonable test case to add here to confirm this is fixed and close it?
comment:18 Changed 9 months ago by kcrisman
- Report Upstream changed from Fixed upstream, but not in a stable release. to Fixed upstream, in a later stable release.
comment:19 Changed 7 months ago by rws
- Description modified (diff)
- Summary changed from Incorrect integral from Maxima to doctest fixed integral from Maxima
Here's the doctest:
sage: assume(1-e^2>0) sage: assume(abs(e)-sqrt(1-e^2)-1>0) sage: assume(abs(sqrt(1-e^2)-1)-abs(e)>0) sage: integrate(cos(w+T)/(1+e*cos(T))^2,T,0,2*pi) 2*pi*sqrt(-e^2 + 1)*e*cos(w)/(e^4 - 2*e^2 + 1)
comment:20 Changed 7 months ago by rws
- Branch set to u/rws/doctest_fixed_integral_from_maxima
comment:21 Changed 7 months ago by rws
- Commit set to fab73690cd00e86c063be62e578a502267e7db94
- Status changed from new to needs_review
New commits:
fab7369 | 8728: doctest |
comment:22 Changed 7 months ago by pbruin
- Status changed from needs_review to needs_work
Your assumptions are contradictory: the first assumption (1 - e^2 > 0) implies the negation of the other two assumptions (see also comment:15).
A fortiori, the other two assumptions (after negating) are actually redundant. It is annoying that we have to add them; ideally, we would only declare this integral to be "fixed" if Maxima did not need the extra two assumptions...
I wonder if this is another manifestation of this bug: