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-MFra-21-Topaz II
21-Topaz II
June 9, 2017
Solved

Solving two simple ordinary differential equations with odesolve. Why the second one fails?

Hi all!

Maybe I'm losing in a glass of water, but I can not solve the second differential equation with odesolve, in the problem hereunder exposed. What's wrong?

two simple odes.jpg

ViktorKorobovAnswer
1-Visitor
June 9, 2017

Dear F.M.,

Choose the method for solving the ODE by right-clicking on Odesolve: Adaptive instead AdamsBDF.

two_eq.png

Viktor

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9 replies

vlehner1-Visitor
1-Visitor
June 9, 2017

Hi F.M.

I'm missing the equation Fy(x) in the solver.

(or is it F0y(x)?) if yes, i got this solution:

is this right?

Best Regards, Volker

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-MFra-21-Topaz IIAuthor
21-Topaz II
June 9, 2017

Thanks Volker,

This is a basic case and I need to check out the results.

In the general case, the analytical solution of the first equation is not known. It is used in the second where the problem arises.

Greetings

Frank

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vlehner1-Visitor
1-Visitor
June 9, 2017

Hi Frank,

And the answer is sooooooo easy with the choice of Adaptive mode.

You can keep your sheet like it was in the origin and change only to adaptive and it works perfectly.

Viktor is absolutely right.

Man lernt nie aus....

Greetings, Volker

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ViktorKorobov1-VisitorAnswer
1-Visitor
June 9, 2017

Dear F.M.,

Choose the method for solving the ODE by right-clicking on Odesolve: Adaptive instead AdamsBDF.

two_eq.png

Viktor

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    -MFra-21-Topaz IIAuthor
    21-Topaz II
    June 9, 2017

    Hi Viktor,

    thank you very much.

    Greetings

    Frank

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    ViktorKorobov1-Visitor
    1-Visitor
    June 9, 2017

    Frank, I was glad to help. But I do not know why Adams/BDF-method not work here.

    Viktor

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