[petsc-users] ODE solving

[Xuan Yu]

On Oct 21, 2010, at 5:56 PM, Matthew Knepley wrote:

> On Thu, Oct 21, 2010 at 4:46 PM, Xuan Yu <xxy113 at psu.edu> wrote:
> Hi
> 
> 
> I am using Petsc solve ODE nonlinear problem.
> 
> I was told to use direct method: umfpackage because of the jacobian matrix is 1860 by 1860.
> 
> But the time consumption is still too big:
> 
> TSSetType(ts,TSBEULER)
> 
> time ./pihm -log_summary -ksp_type preonly -pc_type lu -pc_factor_mat_solver_package umfpack
> 
> I got the result:
>  
> 
> When I use TSSetType(ts,TSSUNDIALS), it is fast:
> 
> 
> 
> How can I find the reason why BEULER is so slow?
> 
> You SNES is not converging. You solve 163 systems, but do 4300 function evaluations.

Could you please tell me more solution options or possible mistakes in my code?


> 
>    Matt
>  
> Thanks
> 
> Xuan
> 
> 
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener

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