[petsc-dev] Missing Fortran interfaces

[Barry Smith]

  John,

   We can provide any Fortran stubs you need but before we do could you please outline to us (in algebraic notation; not in reference to PETSc code) how you plan to handle your "variable switching". That is, what is the problem being solved, what are the constraints, when do you need to switch variables etc?

I would say everyone who has tried to do variable switching in PETSc before has failed because we (the PETSc developers) did not help them enough and  understand what is needed in the Newton solver. I suspect we need to provide a bit more functionality in PETSc to make variable switching a success and I'd like to understand what that is and add it to the PETSc algorithms. Also if you know of any references that actually explain variable switching in detail, that would be great, all I've found are vague hand-wavy discussions that leave too many important details unexplained.

  Thanks

  Barry

> On Jun 12, 2015, at 5:54 PM, John O'Sullivan <jp.osullivan at auckland.ac.nz> wrote:
> 
> Hi,
> 
> We're working on changing variables during an SNES solve so that we can handle phase changes.
> 
> I'm looking into using SNESSetUpdate but there doesn't seem to be a fortran interface. I get an error:
> 
> Undefined symbols for architecture x86_64:
>   "_snessetupdate_", referenced from:
>       _MAIN__ in phaseChange.o
> 
> I've looked in the interface files and can't find it either. I tried writing one myself but things get a bit too complicated to guess...
> 
> Can an interface be added please?
> 
> Is this the best to do variable switching? If not where would be the right place and are there Fortran interfaces? We will be changing from Pressure, Temperature to Pressure, Saturation etc. But for now I'm just working on a simple example code. 
> 
> Cheers
> John
> --
> Dr John O'Sullivan
> Lecturer
> Department of Engineering Science
> University of Auckland, New Zealand
> email: 
> jp.osullivan at auckland.ac.nz
> 
> tel: +64 (0)9 923 85353
>