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05-12-2020
09:19 AM

05-12-2020
09:19 AM

Non linear coupled differential equation system

Hi, can anynone help me please?!

I'm trying to solve this sistem of two couple differential equations but I'm not getting sucess. (I guess that the error is in the red highlighted in the second equation)

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5 REPLIES 5

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05-12-2020
10:26 AM

05-12-2020
10:26 AM

Re: Non linear coupled differential equation system

I don't think you can use a derivative in the function vector for a differential system solver.

You may need to expand the vector with one more element.

Success!

Luc

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05-12-2020
11:31 AM

05-12-2020
11:31 AM

Re: Non linear coupled differential equation system

Hi LucMeekes, thanks for your answer.

But how to expand the vector? The problem have two defree of freedom, I don't know how to expand the vector using Rkfixed comand

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05-12-2020
11:56 AM

05-12-2020
11:56 AM

Re: Non linear coupled differential equation system

I can't see your Prime file, but judging by the PNG file, you need to do something like the following:

(for "exolicit" read "explicit" !!!)

Alan

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05-12-2020
12:49 PM

05-12-2020
12:49 PM

Re: Non linear coupled differential equation system

Hi Alan,

attached is the OP's file for Prime2.

I had to zip it, because the forum is running stupid again.

Luc

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05-13-2020
05:15 AM

05-13-2020
05:15 AM

Re: Non linear coupled differential equation system

Thanks Luc,

Attached is my Prime 2 working version (no idea if the results make sense or not!!)

.

Alan