[petsc-users] SNESSetUp

[Mark F. Adams]

> 
> It seems like first, the (snes->vec_rhs  == snes->vec_sol) test should be moved to SNESSolve where these are apparently set.
> 
> This is not good enough since the next lines will fail if snes->vec_sol is NULL.

That's what I suggested below.  I can test this now if you like.

Mark

> I think we do not to substitute vec_func for vec_sol, but
> we also need to move creation of the update vector since it must be the size of the solution. Will do it now.
> 
>    Matt
>  
> Second can we use snes->vec_func instead of snes->vec_sol here?  This would remove all dependance on vec_rhs and vec_sol in SNESSetup.
> 
> Mark
> 
>   !  Extract global and local vectors from DM; then duplicate for remaining
>   !     vectors that are the same types
>   call MatGetVecs(solver%KKTmat,solver%xVec2,solver%bVec2,ierr)
>   call VecDuplicate(solver%bVec2,solver%rVec2,ierr)
> 
>   call SNESSetDM(solver%snes,solver%da,ierr)
> 
>   ! call SNESSetApplicationContext(solver%snes,solver,ierr)
>   ! call SNESSetApplicationContext(solver%snes,grid,ierr)
> 
>   !  Set function evaluation routine and vector
>   call SNESSetFunction(solver%snes,solver%rVec2,FormFunction,solver,ierr)
> 
>   call SNESSetJacobian(solver%snes,solver%KKTmat,solver%KKTmat,FormJacobian,solver,ierr)
> 
>   ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>   !  Customize nonlinear solver; set runtime options
>   ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>   !  Set runtime options (e.g., -snes_monitor -snes_rtol <rtol> -ksp_type <type>)
>   call SNESSetFromOptions(solver%snes,ierr)
> 
>   call SNESSetUp(solver%snes,ierr) ! pre setup, same as (old) KSP
> 
> 
> 
> 
> 
> -- 
> 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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