ASKSAGE: Sage Q&A Forum - Individual question feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Tue, 03 Feb 2015 08:22:36 -0600cannot calculate limithttps://ask.sagemath.org/question/25647/cannot-calculate-limit/No answer from Sage-6.4.1 for this limit :
var('n');
u = (1+sqrt(n))^(-n);
limit(u(n=n+1)/u,n=infinity)
Sage 4.7 gives 0 (correct). Why ?Fri, 30 Jan 2015 04:20:28 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/Comment by rws for <p>No answer from Sage-6.4.1 for this limit :</p>
<p>var('n');
u = (1+sqrt(n))^(-n);
limit(u(n=n+1)/u,n=infinity)</p>
<p>Sage 4.7 gives 0 (correct). Why ?</p>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25665#post-id-25665This is now http://trac.sagemath.org/ticket/17709Sun, 01 Feb 2015 02:41:48 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25665#post-id-25665Answer by tmonteil for <p>No answer from Sage-6.4.1 for this limit :</p>
<p>var('n');
u = (1+sqrt(n))^(-n);
limit(u(n=n+1)/u,n=infinity)</p>
<p>Sage 4.7 gives 0 (correct). Why ?</p>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?answer=25651#post-id-25651I do not know exactly why, probably a regression in `maxima`. If you really want to know, you should provide a smaller interval of versions than (4.7, 6.4.1) so that we can have a look at the guilty commit. That said, you can still ask `sympy` to do that:
sage: limit(u(n=n+1)/u,n=infinity, algorithm="sympy")
0
Fri, 30 Jan 2015 06:05:31 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?answer=25651#post-id-25651Comment by kcrisman for <p>I do not know exactly why, probably a regression in <code>maxima</code>. If you really want to know, you should provide a smaller interval of versions than (4.7, 6.4.1) so that we can have a look at the guilty commit. That said, you can still ask <code>sympy</code> to do that:</p>
<pre><code>sage: limit(u(n=n+1)/u,n=infinity, algorithm="sympy")
0
</code></pre>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25694#post-id-25694Thanks @robert.marik - I reported this upstream at https://sourceforge.net/p/maxima/bugs/2899/Tue, 03 Feb 2015 08:22:36 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25694#post-id-25694Comment by robert.marik for <p>I do not know exactly why, probably a regression in <code>maxima</code>. If you really want to know, you should provide a smaller interval of versions than (4.7, 6.4.1) so that we can have a look at the guilty commit. That said, you can still ask <code>sympy</code> to do that:</p>
<pre><code>sage: limit(u(n=n+1)/u,n=infinity, algorithm="sympy")
0
</code></pre>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25673#post-id-25673The maxima command is: limit((1+sqrt(n+1))^(-n-1)/(1+sqrt(n))^(-n),n,inf)
Returns zero with Maxima 5.24.0 and is not evaluated when running in http://sagecell.sagemath.org/Sun, 01 Feb 2015 16:36:56 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25673#post-id-25673Comment by marguin for <p>I do not know exactly why, probably a regression in <code>maxima</code>. If you really want to know, you should provide a smaller interval of versions than (4.7, 6.4.1) so that we can have a look at the guilty commit. That said, you can still ask <code>sympy</code> to do that:</p>
<pre><code>sage: limit(u(n=n+1)/u,n=infinity, algorithm="sympy")
0
</code></pre>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25652#post-id-25652Thanks ! Note that converting to exponentials works. My best interval is (4.7, 5.8), sorryFri, 30 Jan 2015 06:52:04 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25652#post-id-25652Comment by tmonteil for <p>I do not know exactly why, probably a regression in <code>maxima</code>. If you really want to know, you should provide a smaller interval of versions than (4.7, 6.4.1) so that we can have a look at the guilty commit. That said, you can still ask <code>sympy</code> to do that:</p>
<pre><code>sage: limit(u(n=n+1)/u,n=infinity, algorithm="sympy")
0
</code></pre>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25668#post-id-25668I never used maxima commands (nor maxima itself), but if you give me some hints me how to do that, i will be glad to.work on it.Sun, 01 Feb 2015 11:10:51 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25668#post-id-25668Comment by kcrisman for <p>I do not know exactly why, probably a regression in <code>maxima</code>. If you really want to know, you should provide a smaller interval of versions than (4.7, 6.4.1) so that we can have a look at the guilty commit. That said, you can still ask <code>sympy</code> to do that:</p>
<pre><code>sage: limit(u(n=n+1)/u,n=infinity, algorithm="sympy")
0
</code></pre>
https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25653#post-id-25653This does not evaluate (returns the question) in 5.2. So it's been a while. Thierry, maybe you can isolate the Maxima command and report upstream?Fri, 30 Jan 2015 08:00:35 -0600https://ask.sagemath.org/question/25647/cannot-calculate-limit/?comment=25653#post-id-25653