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2015-03-19 08:12:49 -0500 asked a question how do I revert to a previous version in history

I want revert to a previous version of a worksheet in SMC.

I already found it in the history, now how can replace the current version with an older revision?

2015-03-19 08:09:42 -0500 asked a question What does the "Math processing error" red button means

I noticed that while I was running some code in a wroksheet in sagemathcloud, a button with red letters saying: "Math processing error" appeared in the toolbar.

when I hover over it, a tooltip appears saying "define symbolic variable".

If I press the button, the following is inserted in the current cell:

%var x, theta

what does this mean? I didn't get any error messages in my code

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2014-12-04 09:19:13 -0500 asked a question Equivalent to Wolfram's Alpha "alternate forms"

In Wolfram's Alpha, when you enter some symbolic expression it will offer you many alternate forms, for example:

is there a way to get similar results in Sage?

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2014-10-09 14:10:29 -0500 asked a question Finding Lyapunov functions in Sage

Is there a way to find Lyapunov functions candidates for a system of ODEs?

see for example:

I know I can simply "do the math" given I have a candidate function, but I wonder if there is any way to quickly explore potential candidates.

2014-08-06 09:25:53 -0500 commented answer How to use R with Sage?

Didn't work for me on Sage 6.1.1. But I found to be due to a bug in the `png` function on R 3.0.2

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2013-09-05 10:37:37 -0500 asked a question Sage starts from console but not from the app menu on OSX

I have installed sage 5.11 but the server does not start from the app menu. However, when I start it from the console, everything works.

any hints?

2013-08-14 08:45:08 -0500 marked best answer Interpreting solution of a system of linear equations

A free parameter, automatically set when the solution is not unique. It should be r1 when you evaluate the cell the first time. Further evaluations increment to r2, r3, ....

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2013-08-13 04:27:35 -0500 asked a question Interpreting solution of a system of linear equations

Hi I am solving the following system:

var('C_at C_au C_bt C_bu I J k_1 k_2 gamma_1 gamma_2')
ss = solve([I-k_1*C_at,k_1*C_at - gamma_1*C_au, k_2*C_bu - gamma_2*C_bt, k_2*C_bu -   gamma_2*C_bt],C_at,C_au,C_bt,C_bu)

and I get the following solution:


what is r8?

2013-07-22 05:39:59 -0500 answered a question How do I install python modules, or use a different version of python? (with sage)

Another possibility, if your package is hosted in the python package index (, is to run the following command:

./sage --python -m easy_install <package_name>
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