[petsc-users] SNESSetUp

[Mark F. Adams]

> 
> Your Fortran is hurting my eyes :)
> 
> Is solver%rVec2 == 0?

Should be OK.  Here is a fuller listing appended.

SNESSetUp seems wrong in that I don't see how SNESSetUp can work unless a user drills though the interface (or I'm missing some SMESSetXXX method or a side effect).  This code is in SNESSetUp:

  ierr = SNESGetFunction(snes,&snes->vec_func,NULL,NULL);CHKERRQ(ierr);
  if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
  if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");

  if (!snes->vec_sol_update /* && snes->vec_sol */) {
    ierr = VecDuplicate(snes->vec_sol,&snes->vec_sol_update);CHKERRQ(ierr);
    ierr = PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);CHKERRQ(ierr);
  }


It seems like first, the (snes->vec_rhs  == snes->vec_sol) test should be moved to SNESSolve where these are apparently set.
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