[Trilinos-Users] Rythmos problem: getStepStatus()

[Cristiano Malossi]

Dear Ross,

thank you for the quick answer. The getPoints() method works for the 
implicit BDF method.
However, for the implicit Runge-Kutta method it seems that the x_dot has 
not been implemented yet:

http://trilinos.sandia.gov/packages/docs/dev/packages/rythmos/doc/html/Rythmos__ImplicitRKStepper__def_8hpp_source.html#l00468

Are the new Rythmos maintainers going to implement that part soon? Thank 
you.
Regards,

    Cristiano


On 01/11/2012 03:34 PM, Bartlett, Roscoe A. wrote:
> Cristiano,
>
> You should be able to get x or x_dot at any point in the range [t, t+dt] for the current time step by calling getPoints(...).  The status returned from getStepStatus() is not really supposed to give all info, just the "free" stuff.
>
> Some of the newer Rythmos maintainers may be able to provide more detail.
>
> -Ross
>
> P.S. AKA rabartl
>
>
>> -----Original Message-----
>> From: trilinos-users-bounces at software.sandia.gov [mailto:trilinos-users-
>> bounces at software.sandia.gov] On Behalf Of Cristiano Malossi
>> Sent: Wednesday, January 11, 2012 9:22 AM
>> To: trilinos-users at software.sandia.gov
>> Subject: [Trilinos-Users] Rythmos problem: getStepStatus()
>>
>> Hello,
>>
>> I have a question about Rythmos. In particular, I am using the Implicit
>> BDF stepper, that integrates DAEs with a variable step size. The solver
>> apparently works, however I cannot access the derivative of the
>> solution, that I need.
>>
>> On line 487 of the file Rythmos_ImplicitBDFStepper_def.hpp it is written:
>>
>>     stepStatus.solutionDot = Teuchos::null; // This is *not* free!
>>
>> where it is not clear to me what the comment means.
>> On the top of the method there is another comment:
>>
>>     // 2007/08/24: rabartl: We agreed that getStepStatus() would be free
>>     // so I have commented out removed all code that is not free
>>
>> In the documentation it is written that the code is a re-implementation
>> of LLNL Sundials IDA library, that should be free. Could you please give
>> me some information about this issue? It is possible to fix this method
>> or have a patch to make it working?
>>
>> Note that the same problem appears with the Implicit Runge-Kutta method.
>>
>> Thank you.
>> Best regards,
>>
>>       Cristiano Malossi
>>
>> --
>>          Cristiano Malossi
>>          Ph.D. Student
>>
>>          EPFL - SB - SMA - MATHICSE
>>          CMCS - Modelling and Scientific Computing
>>          Office MA C2 577, Av.Piccard, Station 8.
>>          CH-1015 Lausanne (Switzerland)
>>          Ph.    : +41 21 69 32733
>>          E-mail : cristiano.malossi at epfl.ch
>>
>>
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>> Trilinos-Users at software.sandia.gov
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-- 
        Cristiano Malossi
        Ph.D. Student

        EPFL - SB - SMA - MATHICSE
        CMCS - Modelling and Scientific Computing
        Office MA C2 577, Av.Piccard, Station 8.
        CH-1015 Lausanne (Switzerland)
        Ph.    : +41 21 69 32733
        E-mail : cristiano.malossi at epfl.ch