1:  #include <petsc/private/snesimpl.h>

  3: typedef struct {
  4:   PetscBool transpose_solve;
  5: } SNES_KSPONLY;

  7: static PetscErrorCode SNESSolve_KSPONLY(SNES snes)
  8: {
  9:   SNES_KSPONLY   *ksponly = (SNES_KSPONLY*)snes->data;
 11:   PetscInt       lits;
 12:   Vec            Y,X,F;

 15:   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);

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

 23:   X = snes->vec_sol;
 24:   F = snes->vec_func;
 25:   Y = snes->vec_sol_update;

 27:   SNESComputeFunction(snes,X,F);
 28:   if (snes->numbermonitors) {
 29:     PetscReal fnorm;
 30:     VecNorm(F,NORM_2,&fnorm);
 31:     SNESMonitor(snes,0,fnorm);
 32:   }

 34:   /* Call general purpose update function */
 35:   if (snes->ops->update) {
 36:     (*snes->ops->update)(snes, 0);
 37:   }

 39:   /* Solve J Y = F, where J is Jacobian matrix */
 40:   SNESComputeJacobian(snes,X,snes->jacobian,snes->jacobian_pre);

 42:   SNESCheckJacobianDomainerror(snes);

 44:   KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
 45:   if (ksponly->transpose_solve) {
 46:     KSPSolveTranspose(snes->ksp,F,Y);
 47:   } else {
 48:     KSPSolve(snes->ksp,F,Y);
 49:   }
 50:   snes->reason = SNES_CONVERGED_ITS;
 51:   SNESCheckKSPSolve(snes);

 53:   KSPGetIterationNumber(snes->ksp,&lits);
 54:   PetscInfo2(snes,"iter=%D, linear solve iterations=%D\n",snes->iter,lits);
 55:   snes->iter++;

 57:   /* Take the computed step. */
 58:   VecAXPY(X,-1.0,Y);
 59:   if (snes->numbermonitors) {
 60:     PetscReal fnorm;
 61:     SNESComputeFunction(snes,X,F);
 62:     VecNorm(F,NORM_2,&fnorm);
 63:     SNESMonitor(snes,1,fnorm);
 64:   }
 65:   return(0);
 66: }

 68: static PetscErrorCode SNESSetUp_KSPONLY(SNES snes)
 69: {

 73:   SNESSetUpMatrices(snes);
 74:   return(0);
 75: }

 77: static PetscErrorCode SNESDestroy_KSPONLY(SNES snes)
 78: {

 82:   PetscFree(snes->data);
 83:   return(0);
 84: }

 86: /* -------------------------------------------------------------------------- */
 87: /*MC
 88:       SNESKSPONLY - Nonlinear solver that only performs one Newton step and does not compute any norms.
 89:       The main purpose of this solver is to solve linear problems using the SNES interface, without
 90:       any additional overhead in the form of vector operations.

 92:    Level: beginner

 94: .seealso:  SNESCreate(), SNES, SNESSetType(), SNESNEWTONLS, SNESNEWTONTR
 95: M*/
 96: PETSC_EXTERN PetscErrorCode SNESCreate_KSPONLY(SNES snes)
 97: {
 98:   SNES_KSPONLY   *ksponly;

102:   snes->ops->setup          = SNESSetUp_KSPONLY;
103:   snes->ops->solve          = SNESSolve_KSPONLY;
104:   snes->ops->destroy        = SNESDestroy_KSPONLY;
105:   snes->ops->setfromoptions = 0;
106:   snes->ops->view           = 0;
107:   snes->ops->reset          = 0;

109:   snes->usesksp = PETSC_TRUE;
110:   snes->usesnpc = PETSC_FALSE;

112:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

114:   PetscNewLog(snes,&ksponly);
115:   snes->data = (void*)ksponly;
116:   return(0);
117: }

119: /*MC
120:       SNESKSPTRANSPOSEONLY - Nonlinear solver that only performs one Newton step and does not compute any norms.
121:       The main purpose of this solver is to solve transposed linear problems using the SNES interface, without
122:       any additional overhead in the form of vector operations within adjoint solvers.

124:    Level: beginner

126: .seealso:  SNESCreate(), SNES, SNESSetType(), SNESKSPTRANSPOSEONLY, SNESNEWTONLS, SNESNEWTONTR
127: M*/
128: PETSC_EXTERN PetscErrorCode SNESCreate_KSPTRANSPOSEONLY(SNES snes)
129: {
130:   SNES_KSPONLY   *kspo;

134:   SNESCreate_KSPONLY(snes);
135:   kspo = (SNES_KSPONLY*)snes->data;
136:   kspo->transpose_solve = PETSC_TRUE;
137:   return(0);
138: }