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Condition of type: SIMPLE-CONDITION

asked 2014-07-16 09:18:33 -0600

Caterpillar gravatar image

updated 2014-07-17 00:52:05 -0600

Executing

limit(((x^(2*x)-2*factorial(x)+x*log(x,10))^((x^(2*x))/factorial(x)))/(x^(((2*x)^(2*x))/(factorial(x-1)))),x=infinity)

on my Sagemath's server web interface, I obtain:

Condition of type: SIMPLE-CONDITION
Undefined limit product $INFINITY * $ZEROA in lim-times
Available restarts:

1. (CONTINUE) Return from BREAK.

Top level in: #<process TOP-LEVEL>.
>

What can I do?

'Sage Version 6.1.1, Release Date: 2014-02-04'

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answered 2014-07-16 13:16:27 -0600

Sage delegates treatment of 'limit' expressions to Maxima. When Maxima has questions while evaluating an expression, it asks the user. Here: Maxima tries to compute the limit of a product as the product of limits, and is stuck because one limit is infinite and the other is zero. So Maxima is asking you what to do from there.

When Sage delegates a computation to Maxima and Maxima asks for user input, as above, in some cases Sage can figure out what the question is, and tell you about it, for example if you need to specify the sign of some variable. In other cases Sage cannot make a good enough guess of what Maxima is asking or complaining about, and it will either hand you Maxima's question as is, or keep the expression unevaluated.

Apparently in the version and mode of Sage you are running, it hands you Maxima's question, while in the version and mode of Sage I'm using, it keeps the expression unevaluated. This might be due to some change in the interface between Sage and Maxima in recent versions, or have to do with how Sage is used (command-line vs notebook vs IPython notebook).

I tried with Sage 6.2.beta5 and 6.3.beta5, both in command-line and notebook, and always got the expression back, unchanged.

sage: version()
'Sage Version 6.2.beta5, Release Date: 2014-03-23'
sage: limit(((x^(2*x)-2*factorial(x)+x*log(x,10))^((x^(2*x))/factorial(x)))/(x^(((2*x)^(2*x))/(factorial(x-1)))),x=infinity)
limit((x^(2*x) + x*log(x)/log(10) - 2*factorial(x))^(x^(2*x)/factorial(x))*x^(-(2*x)^(2*x)/factorial(x - 1)), x, +Infinity)

I don't have easy access to Sage 6.1.1 to test on that version. When you say "my Sagemath's server web interface", do you mean you are running sage -notebook on your computer (or sage, then notebook()), or connecting to some sage notebook server on the web?

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"my Sagemath's server web interface", I mean I am running sage, then notebook() on a remote server your and I connect to with a browser.

Caterpillar gravatar imageCaterpillar ( 2014-07-16 14:37:13 -0600 )edit

The sage notebook server at http://sagenb.mc.edu/ has version 6.1.1, but I don't have an account there. Other sage notebook servers I'm aware of are running 4.7.2, 4.8, 5.8, 5.11. If you tell me the url of the "remote server you and I can connect to with a browser", I can play with your code there and try to give you more specific details for Sage 6.1.1. Otherwise you can also create an account on the SageMathCloud at cloud.sagemath.org, the version of Sage there is currently 6.2.rc2, and I think the next upgrade planned is 6.3 when 6.3 gets released, which should be some time this summer.

slelievre gravatar imageslelievre ( 2014-07-16 17:06:14 -0600 )edit

how can I send it to you privately? I cannot find a private message button on ask.sagemath.org

Caterpillar gravatar imageCaterpillar ( 2014-07-17 02:47:51 -0600 )edit

Private message is not yet implemented in askbot, although it's a frequently requested feature. I added a url to my profile, you can find my email address from there.

slelievre gravatar imageslelievre ( 2014-07-17 08:09:47 -0600 )edit

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Asked: 2014-07-16 09:18:33 -0600

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Last updated: Jul 16 '14