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Non linear coupled differential equation system

IgorBraz
4-Participant

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)

5 REPLIES 5
LucMeekes
23-Emerald III
(To:IgorBraz)

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

IgorBraz
4-Participant
(To:LucMeekes)

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

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

 

g0.jpg

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

 

Alan

LucMeekes
23-Emerald III
(To:AlanStevens)

Hi Alan,

 

attached is the OP's file for Prime2.

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

 

Luc

Thanks Luc,

 

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

 

g0.JPGg1.JPGg2.JPG.

 

Alan

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