[petsc-users] TSSetMatrices structure?

[Matthew Knepley]

On Thu, Mar 29, 2012 at 9:09 PM, Andrew Spott <andrew.spott at gmail.com>wrote:

> Thanks again for the quick reply!  Thankfully I don't have a mass matrix,
> I'm just solving the schrodinger equation.
>

Depending on how you discretize, you can have a mass matrix for Schrodinger.

   Matt


> 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   These are outdated manual pages; you'll want to avoid this.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
> >>>
> >>
> >
>
>


-- 
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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