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Best answer by Werner_E

You wrote "y" where you should have written "y(x)"

 

Do you really mean y(x^2) in the second derivative and not just y(x)?

 

Mathcad does fine with y(x)

Werner_E_0-1623529781797.png

 

1 reply

W
Werner_E25-Diamond IAnswer
25-Diamond I
June 12, 2021

You wrote "y" where you should have written "y(x)"

 

Do you really mean y(x^2) in the second derivative and not just y(x)?

 

Mathcad does fine with y(x)

Werner_E_0-1623529781797.png

 

    A
    AS_99655001-VisitorAuthor
    1-Visitor
    June 12, 2021

    Thank you very much. You are very helpful, This is my second day learning mathcad.

     

    For the second derivative it is y"(x^2). I don't understand either. Can you give me a reason for this?

    Now there is a new problem again. In Mathcad Prime 7 it is readable. But in Mathcad 15 it can't. Please let me know.

    Can you please find a solution?

    W
    Werner_E25-Diamond I
    25-Diamond I
    June 13, 2021

    I don't have Prime 7 installed so I can't read your P7 file.

    In your MC15 file you will have to define D as a function of x and w and not of v and w.
    But you are solving a quite different ODE (system) using rkfixed compared to the one with odesolve

    Werner_E_0-1623545999807.pngWerner_E_0-1623546427477.png

    To solve the same ODE with rkfixed as with odesolve, you would do like this:

    Werner_E_0-1623546866455.png

     

     

    Note that you don't need to define a range for x!

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