Comments (13)
That's a boundary value problem. You gave it an ODE solver, not a BVP solver. That doesn't make sense. See the tutorial on BVPs: https://docs.sciml.ai/DiffEqDocs/stable/tutorials/bvp_example/. You need to use a solver for BVPs, like Shooting(Rosenbrock23())
.
from differentialequations.jl.
That's a boundary value problem. You gave it an ODE solver, not a BVP solver. That doesn't make sense. See the tutorial on BVPs: https://docs.sciml.ai/DiffEqDocs/stable/tutorials/bvp_example/. You need to use a solver for BVPs, like
Shooting(Rosenbrock23())
.
Thanks for the reply.Before this, I have used the Shooting(Vern8())
method to solve the BVP problem, but the results are still aborting, I think there may be a problem with my model settings and boundary condition settings, but I don't know where the problem is.
from differentialequations.jl.
What is the error message or warning? Is the model stiff? You show a stiff ODE solver earlier, but now you're showing a method only for non-stiff equations.
from differentialequations.jl.
I tested this problem on the latest version of BoundaryValueDiffEq.jl:
- Single Shooting: warning dt<=dtmin, Failure retcode
- Multiple Shooting: warning dt<=dtmin, Successful retcode
- MIRK methods: no warning, Successful retcode
Final solution:
from differentialequations.jl.
I tested this problem on the latest version of BoundaryValueDiffEq.jl:
- Single Shooting: warning dt<=dtmin, Failure retcode
- Multiple Shooting: warning dt<=dtmin, Successful retcode
- MIRK methods: no warning, Successful retcode
Final solution:
yes, it is the right result.I have caculated out by python.But when i use julia,it takes a very long time to use MIRK method,so i just use the shooting .I do not know the reason why it is useless for shooting- _ -
from differentialequations.jl.
What is the error message or warning? Is the model stiff? You show a stiff ODE solver earlier, but now you're showing a method only for non-stiff equations.
sorry, the model is stiff . Just like the next follower shows , it can be solved by MIRK method , but not for shooting
from differentialequations.jl.
I tested this problem on the latest version of BoundaryValueDiffEq.jl:
- Single Shooting: warning dt<=dtmin, Failure retcode
- Multiple Shooting: warning dt<=dtmin, Successful retcode
- MIRK methods: no warning, Successful retcode
Final solution:
How long it takes by using MIRK method?
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orry, the model is stiff . Just like the next follower shows , it can be solved by MIRK method , but not for shooting
Yes that's expected. Shooting methods are not as stable as collocation methods, and so for sufficiently difficult problems it will be only the MIRK and similar methods that are stable.
from differentialequations.jl.
orry, the model is stiff . Just like the next follower shows , it can be solved by MIRK method , but not for shooting
Yes that's expected. Shooting methods are not as stable as collocation methods, and so for sufficiently difficult problems it will be only the MIRK and similar methods that are stable.
Thank you for your help!
from differentialequations.jl.
But when i use julia,it takes a very long time to use MIRK method,so i just use the shooting .I do not know the reason why it is useless for shooting- _ -
Could you show the version of BoundaryValueDiffEq.jl you are using? It is pretty fast here to get the final result using MIRK methods. @HaoJieZhang0917
from differentialequations.jl.
orry, the model is stiff . Just like the next follower shows , it can be solved by MIRK method , but not for shooting
Yes that's expected. Shooting methods are not as stable as collocation methods, and so for sufficiently difficult problems it will be only the MIRK and similar methods that are stable.
i have another question , can the parameter tspan be set to a non-equidistant mesh?similar to the Chebyshev method.
from differentialequations.jl.
But when i use julia,it takes a very long time to use MIRK method,so i just use the shooting .I do not know the reason why it is useless for shooting- _ -
Could you show the version of BoundaryValueDiffEq.jl you are using? It is pretty fast here to get the final result using MIRK methods. @HaoJieZhang0917
The verson of BoundaryValueDiffEq.jl is v4.0.1 . I almost need 15 mins to caculate it through i have setted the dt=0.5...
from differentialequations.jl.
That compile time is fixed with Julia v1.1.0.
from differentialequations.jl.
Related Issues (20)
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