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ViktorKorobov1-Visitor
1-Visitor
Aug 8, 2014 8:42 AM UTC
Question

Prime 3.0 can't solve BVP with units?

Prime 3.0 can't solve BVP with units?

Without units - no problem:

BVP.PNG

With units - error:

BVP1.PNG

Viktor

6 replies

Werner_E
Werner_E25-Diamond I
25-Diamond I
Aug 8, 2014 8:55 AM UTC

C:=Odesolve..., not C(x):=Odesolve...!

Unfortunately this does not solve the problem.

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ViktorKorobov1-VisitorAuthor
1-Visitor
Aug 8, 2014 9:01 AM UTC

Thank you Werner, but the problem remains

BVP_1a.PNG

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Werner_E
Werner_E25-Diamond I
25-Diamond I
Aug 8, 2014 9:27 AM UTC

Yes, I already relaized that. It seems to be a bug in Prime and has to do with the units in combination with that kind of boundary conditions.

If I replace one of your conditions with a more "standard" one, Prime seems to be happy. Of course thats not a solution to your problem, though.

1.png

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HarveyHensley12-Amethyst
12-Amethyst
Aug 9, 2014 2:31 PM UTC

Viktor,

This problem is discussed at this link. It's a problem caused by sbval not attaching the units to the estimated initial condition. If you run sbval separately as Josue eventually did and then reattaching the unit to the new initial condition, it works.

Also, see here for other units problems with odesolve. It explains why odesolve sometimes works with units and sometime not. When it doesn't work, try using Rkadapt, line solver routine.

Harvey

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ViktorKorobov1-VisitorAuthor
1-Visitor
Aug 10, 2014 4:58 PM UTC

Thank you Harvey.

Viktor

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