Actual source code: preonly.c

 2:  #include src/ksp/ksp/kspimpl.h

  6: static PetscErrorCode KSPSetUp_PREONLY(KSP ksp)
  7: {
  9:   return(0);
 10: }

 14: static PetscErrorCode  KSPSolve_PREONLY(KSP ksp)
 15: {
 17:   Vec            X,B;
 18:   PetscTruth     diagonalscale;

 21:   PCDiagonalScale(ksp->pc,&diagonalscale);
 22:   if (diagonalscale) SETERRQ1(PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",ksp->type_name);
 23:   if (!ksp->guess_zero) {
 24:     SETERRQ(PETSC_ERR_USER,"Running KSP of preonly doesn't make sense with nonzero initial guess\n\
 25:                you probably want a KSP type of Richardson");
 26:   }
 27:   ksp->its    = 0;
 28:   X           = ksp->vec_sol;
 29:   B           = ksp->vec_rhs;
 30:   KSP_PCApply(ksp,B,X);
 31:   ksp->its    = 1;
 32:   ksp->reason = KSP_CONVERGED_ITS;
 33:   return(0);
 34: }

 36: /*MC
 37:      KSPPREONLY - This implements a stub method that applies ONLY the preconditioner.
 38:                   This may be used in inner iterations, where it is desired to 
 39:                   allow multiple iterations as well as the "0-iteration" case. It is 
 40:                   commonly used with the direct solver preconditioners like PCLU and PCCHOLESKY

 42:    Options Database Keys:
 43: .   see KSPSolve()

 45:    Level: beginner

 47: .seealso:  KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP

 49: M*/

 54: PetscErrorCode KSPCreate_PREONLY(KSP ksp)
 55: {
 57:   ksp->data                      = (void*)0;
 58:   ksp->ops->setup                = KSPSetUp_PREONLY;
 59:   ksp->ops->solve                = KSPSolve_PREONLY;
 60:   ksp->ops->destroy              = KSPDefaultDestroy;
 61:   ksp->ops->buildsolution        = KSPDefaultBuildSolution;
 62:   ksp->ops->buildresidual        = KSPDefaultBuildResidual;
 63:   ksp->ops->setfromoptions       = 0;
 64:   ksp->ops->view                 = 0;
 65:   return(0);
 66: }