adding support for custom call to inner linear solve in SNES

[Barry Smith]

  Lisandro,

    What problem is this suppose to be solving? Can you give an
example of linsolve()?
  
   Barry


On Tue, 7 Aug 2007, Lisandro Dalcin wrote:

> I would like to add some support in SNES to enable users to customize
> the inner call to KSPSolve(). The approach amount to implement
> something like this:
> 
> #undef __FUNCT__
> #define __FUNCT__ "SNES_KSPSolve"
> PetscErrorCode SNES_KSPSolve(SNES snes, KSP ksp, Vec b, Vec x)
> {
>   PetscErrorCode ierr;
> 
>   PetscFunctionBegin;
>   if (snes->ksp_ewconv) { ierr =
> SNESKSPEW_PreSolve(snes,ksp,b,x);CHKERRQ(ierr);  }
>   if (snes->ops->linsolve) {
>     ierr = (*snes->ops->linsolve)(snes, ksp, b, x);CHKERRQ(ierr);
>   } else {
>     ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
>   }
>   if (snes->ksp_ewconv) { ierr =
> SNESKSPEW_PostSolve(snes,ksp,b,x);CHKERRQ(ierr); }
>   PetscFunctionReturn(0);
> }
> 
> and, of course, add a routine to let users set their custom linear
> solve routine.
> 
> Is this fine? Is it open-door for too-much user hackery? There could
> be a better way to enable something like this?
> 
> I am also thinking (if there is no objection) in adding support for
> setting a PreSolve and a PostSolve routine, but not sure what the
> interface of the callback functions should be, and if the presolve
> routine should be called after of before SNESSetUp().
> 
> 
>