Date: 2013-07-02T14:48:20+00:00

Actual source code: preonly.c
petsc-3.4.2 2013-07-02

      2: #include <petsc-private/kspimpl.h>

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

     14: static PetscErrorCode  KSPSolve_PREONLY(KSP ksp)
     15: {
     17:   PetscBool      diagonalscale;

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

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

     38:    Options Database Keys:
     39: .   see KSPSolve()

     41:    Level: beginner

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

     45: M*/

     49: PETSC_EXTERN PetscErrorCode KSPCreate_PREONLY(KSP ksp)
     50: {

     54:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,2); /* LEFT/RIGHT is arbitrary, so "support" both */
     55:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);

     57:   ksp->data                = (void*)0;
     58:   ksp->ops->setup          = KSPSetUp_PREONLY;
     59:   ksp->ops->solve          = KSPSolve_PREONLY;
     60:   ksp->ops->destroy        = KSPDestroyDefault;
     61:   ksp->ops->buildsolution  = KSPBuildSolutionDefault;
     62:   ksp->ops->buildresidual  = KSPBuildResidualDefault;
     63:   ksp->ops->setfromoptions = 0;
     64:   ksp->ops->view           = 0;
     65:   return(0);
     66: }