[petsc-users] TSSetMatrices structure?

[Barry Smith]

   Thats the first time I've seen __"just"__ solving the schrodinger equation :-)

   Barry



On Mar 29, 2012, at 9:09 PM, Andrew Spott wrote:

> Thanks again for the quick reply!  Thankfully I don't have a mass matrix, I'm just solving the schrodinger equation.
> 
> Thanks again.
> 
> -Andrew
> 
> On Mar 29, 2012, at 8:07 PM, Barry Smith wrote:
> 
>> 
>> On Mar 29, 2012, at 8:58 PM, Andrew Spott wrote:
>> 
>>> This: http://www.mcs.anl.gov/petsc/petsc-3.2/src/ts/examples/tutorials/ex4.c.html  Looks like what I'm interested in doing, though I would like to use the latest.
>> 
>>  With this simple a situation using the current version or switching to dev is both fine. The changes you would have to make are small 
>> 
>>> When is Petsc 3.3 (or 3.4, I'm not sure how your versioning works) coming out?  Is the dev version stable enough (in API and in execution) to be used?
>> 
>>   The dev version is always stable enough to use :-). At this point yes because we are in the testing phase for the next release.
>> 
>>> 
>>> Until then, does the 3.2 version of the TS interface work?  (the link above, and the corresponding one for petsc-dev don't appear to have much changed between them).
>> 
>>  Yes.
>> 
>>  Barry
>> 
>> Note that in 3.2 if you have a mass matrix (for example    M U_t  = A U_xx)how to formulate the problem is different between 3.2 and dev so I would recommend working immediately with dev.  But for simple U_t  = something, 3.2 is fine and then you can change it slightly for the next release.
>> 
>>> 
>>> Thanks for the prompt reply,
>>> 
>>> -Andrew
>>> 
>>> On Mar 29, 2012, at 7:37 PM, Barry Smith wrote:
>>> 
>>>> 
>>>> Andrew,
>>>> 
>>>>  These are outdated manual pages; you'll want to avoid this. 
>>>> 
>>>>  Jed and Emil have done a major update of the TS interface and solvers, much more powerful and less confusing. 
>>>> 
>>>>   Likely you'll want to use TSSetIFunction() and TSSetIJacobian() http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/TS/index.html and work with petsc-dev http://www.mcs.anl.gov/petsc/developers/index.html
>>>> 
>>>> 
>>>> 
>>>>  Barry
>>>> 
>>>> On Mar 29, 2012, at 8:09 PM, Andrew Spott wrote:
>>>> 
>>>>> In the Petsc manual, there is a TSSetMatrices function, however there is no further documentation for it.
>>>>> 
>>>>> It is referenced in the manual as:
>>>>> 
>>>>> TSSetMatrices(TS ts,
>>>>> Mat A,PetscErrorCode (*frhs)(TS,PetscReal,Mat*,Mat*,MatStructure*,void*), Mat B,PetscErrorCode (*flhs)(TS,PetscReal,Mat*,Mat*,MatStructure*,void*), MatStructure flag,void *ctx)
>>>>> 
>>>>> However, what is passed to the function pointers isn't mentioned anywhere, and it isn't in the online documentation.
>>>>> 
>>>>> Also, I assume that "MatStructure flag" tells if the structure of A and B are the same or different, if B is PETSC_NULL, is flag "SAME_NONZERO_PATERN" or is it different?  (B can be considered to not exist, or to exist as an identity matrix, hence the confusion).
>>>>> 
>>>>> How does the ctx work?  Is the same context passed to frhs each time?
>>>>> 
>>>>> Thanks for the help.
>>>>> 
>>>>> -Andrew
>>>> 
>>> 
>> 
>