Actual source code: ksponly.c
petsc-3.7.1 2016-05-15
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      2: #include <petsc/private/snesimpl.h>

      6: static PetscErrorCode SNESSolve_KSPONLY(SNES snes)
      7: {
      8:   PetscErrorCode     ierr;
      9:   PetscInt           lits;
     10:   Vec                Y,X,F;

     13:   if (snes->xl || snes->xu || snes->ops->computevariablebounds) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE, "SNES solver %s does not support bounds", ((PetscObject)snes)->type_name);

     15:   snes->numFailures            = 0;
     16:   snes->numLinearSolveFailures = 0;
     17:   snes->reason                 = SNES_CONVERGED_ITERATING;
     18:   snes->iter                   = 0;
     19:   snes->norm                   = 0.0;

     21:   X = snes->vec_sol;
     22:   F = snes->vec_func;
     23:   Y = snes->vec_sol_update;

     25:   SNESComputeFunction(snes,X,F);
     26:   if (snes->numbermonitors) {
     27:     PetscReal fnorm;
     28:     VecNorm(F,NORM_2,&fnorm);
     29:     SNESMonitor(snes,0,fnorm);
     30:   }

     32:   /* Call general purpose update function */
     33:   if (snes->ops->update) {
     34:     (*snes->ops->update)(snes, 0);
     35:   }

     37:   /* Solve J Y = F, where J is Jacobian matrix */
     38:   SNESComputeJacobian(snes,X,snes->jacobian,snes->jacobian_pre);
     39:   KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
     40:   KSPSolve(snes->ksp,F,Y);
     41:   snes->reason = SNES_CONVERGED_ITS;
     42:   SNESCheckKSPSolve(snes);

     44:   KSPGetIterationNumber(snes->ksp,&lits);
     45:   snes->linear_its += lits;
     46:   PetscInfo2(snes,"iter=%D, linear solve iterations=%D\n",snes->iter,lits);
     47:   snes->iter++;

     49:   /* Take the computed step. */
     50:   VecAXPY(X,-1.0,Y);
     51:   SNESComputeFunction(snes,X,F);
     52:   if (snes->numbermonitors) {
     53:     PetscReal fnorm;
     54:     VecNorm(F,NORM_2,&fnorm);
     55:     SNESMonitor(snes,1,fnorm);
     56:   }
     57:   return(0);
     58: }

     62: static PetscErrorCode SNESSetUp_KSPONLY(SNES snes)
     63: {

     67:   SNESSetUpMatrices(snes);
     68:   return(0);
     69: }

     73: static PetscErrorCode SNESDestroy_KSPONLY(SNES snes)
     74: {

     77:   return(0);
     78: }

     80: /* -------------------------------------------------------------------------- */
     81: /*MC
     82:       SNESKSPONLY - Nonlinear solver that only performs one Newton step and does not compute any norms.
     83:       The main purpose of this solver is to solve linear problems using the SNES interface, without
     84:       any additional overhead in the form of vector operations.

     86:    Level: beginner

     88: .seealso:  SNESCreate(), SNES, SNESSetType(), SNESNEWTONLS, SNESNEWTONTR
     89: M*/
     92: PETSC_EXTERN PetscErrorCode SNESCreate_KSPONLY(SNES snes)
     93: {

     96:   snes->ops->setup          = SNESSetUp_KSPONLY;
     97:   snes->ops->solve          = SNESSolve_KSPONLY;
     98:   snes->ops->destroy        = SNESDestroy_KSPONLY;
     99:   snes->ops->setfromoptions = 0;
    100:   snes->ops->view           = 0;
    101:   snes->ops->reset          = 0;

    103:   snes->usesksp = PETSC_TRUE;
    104:   snes->usespc  = PETSC_FALSE;

    106:   snes->data = 0;
    107:   return(0);
    108: }