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differential equation problems.

asked 2011-01-18 10:24:58 -0500

mhfrey gravatar image

updated 2011-05-05 08:38:20 -0500

Kelvin Li gravatar image

I am trying to get the differential equation examples to work:

x = var('x') y = function('y',x) desolve(diff(y,x) + y - 1, y)

or

t = var('t') x = function('x',t) DE = diff(x, t) + x - 1 desolve(DE, [x,t])

Both return errors. What am I doing wrong?

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Surprising! I copy pasted both the equations and they work fine for me.

Shashank gravatar imageShashank ( 2011-01-18 12:11:41 -0500 )edit

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answered 2011-01-18 13:54:09 -0500

mhfrey gravatar image

I had to restart and it is working now for both examples. Unfortunately I did not capture the error information. If I see it again I will capture the information and post it.

Thank you for your help.

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answered 2011-01-18 12:14:14 -0500

DSM gravatar image

You may not be doing anything wrong. I got two different kinds of errors:

TypeError: Error executing code in Maxima
CODE:
    sage99 : ('y(x))+(diff('y(x), x, 1))+(-1)$
Maxima ERROR:
     sage99 : ('y(x))+(diff('y(x), x, 1))+(-1)$

stdin:7094:Incorrect syntax: Too many )'s
(%i87) 
stdin:7145:Incorrect syntax: Premature termination of input at $.
(%i88) 

and

sage: desolve(diff(y,x) + y - 1, y)
sage103

before getting the right answer:

sage: desolve(diff(y,x) + y - 1, y)
(c + e^x)*e^(-x)

Then I did it from a restart and everything worked the first time, and I can't reproduce the errors anymore. Looks like the maxima interface can get itself into a state, whether because of something I'd done previously or not. But this definitely shouldn't happen: were these the same kinds of errors you saw?

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Asked: 2011-01-18 10:24:58 -0500

Seen: 252 times

Last updated: Jan 18 '11