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Mar 11, 2014
12:03 PM

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Mar 11, 2014
12:03 PM

Odesolver problem

Hello,

I try to solve a differential equation with the Odesolver.

Unfortunately I don't know how to continue.

It is written, that the variable v.1 in the solution matrix must be a function but it is now any1.

Maybe I just made a small mistake, but I can't find it out.

Thanks for your help

Adrian

p.s I added a Screenshot

Solved! Go to Solution.

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Mar 11, 2014
01:55 PM

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Mar 11, 2014
01:55 PM

I suspect a major part of the problem with this ODE is the relative magnitudes of the numbers involved - F.kolb is very small for all values of t. Re-arranging to put v' on the rhs by itself produces a result; how sensible it is is another matter ...

Stuart

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Mar 11, 2014
12:31 PM

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Mar 11, 2014
12:31 PM

Please post your sheet, not just a pic

We don't see how you had defined the function F().

Try to keep the derivatives on the LHS

Mar 11, 2014
01:02 PM

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Mar 11, 2014
01:33 PM

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Mar 11, 2014
01:33 PM

Hi,

There are a few things that mathcad can't handle in your file.

1. definition for Ihub still has units.

2.You cannot define boundary conditions other than at the start or end of the solve block

So v(0)=0 or v(0.05)=0 would be OK

v(1/75/4)=0 (or (v(0.053) ) isn't.

3. Mathcad needs the differential equations in a standard form d/dx (f(x)= g(x).

Otherwise I think that the problem becomes too ill defined.

Regards

Andy

Mar 11, 2014
01:55 PM

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Mar 11, 2014
01:55 PM

I suspect a major part of the problem with this ODE is the relative magnitudes of the numbers involved - F.kolb is very small for all values of t. Re-arranging to put v' on the rhs by itself produces a result; how sensible it is is another matter ...

Stuart

Mar 11, 2014
02:13 PM

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Mar 11, 2014
02:13 PM

1. Should there be a minus sign in front of the sin term in FKolb?

2. Attached shows how to get the initial velocity that gives zero velocity at time (1/75)/4.

Alan