1: #include <../src/snes/impls/fas/fasimpls.h> /*I  "petscsnes.h"  I*/

  5: /*@
  6:    SNESFASGetGalerkin - Gets if the coarse problems are formed by projection to the fine problem

  8:    Input Parameter:
  9: .  snes - the nonlinear solver context

 11:    Output parameter:
 12: .  flg - the status of the galerkin problem

 14:    Level: advanced

 16: .keywords: FAS, galerkin

 18: .seealso: SNESFASSetLevels(), SNESFASSetGalerkin()
 19: @*/
 20: PetscErrorCode SNESFASGetGalerkin(SNES snes, PetscBool *flg)
 21: {
 22:   SNES_FAS * fas = (SNES_FAS*)snes->data;

 25:   *flg = fas->galerkin;
 26:   return(0);
 27: }

 31: /*@
 32:    SNESFASSetGalerkin - Sets coarse problems as formed by projection to the fine problem

 34:    Input Parameter:
 35: .  snes - the nonlinear solver context
 36: .  flg - the status of the galerkin problem

 38:    Level: advanced

 40: .keywords: FAS, galerkin

 42: .seealso: SNESFASSetLevels(), SNESFASGetGalerkin()
 43: @*/
 44: PetscErrorCode SNESFASSetGalerkin(SNES snes, PetscBool flg)
 45: {
 46:   SNES_FAS       * fas = (SNES_FAS*)snes->data;

 50:   fas->galerkin = flg;
 51:   if (fas->next) {SNESFASSetGalerkin(fas->next, flg);}
 52:   return(0);
 53: }

 57: /*
 58: SNESFASGalerkinDefaultFunction

 60:  */
 61: PetscErrorCode SNESFASGalerkinDefaultFunction(SNES snes, Vec X, Vec F, void * ctx)
 62: {
 63:   /* the Galerkin FAS function evalutation is defined as
 64:    F^l(x^l) = I^l_0F^0(P^0_lx^l)
 65:    */
 66:   SNES           fassnes;
 67:   SNES_FAS       *fas;
 68:   SNES_FAS       *prevfas;
 69:   SNES           prevsnes;
 70:   Vec            b_temp;

 74:   /* prolong to the fine level and evaluate there. */
 75:   fassnes  = (SNES)ctx;
 76:   fas      = (SNES_FAS*)fassnes->data;
 77:   prevsnes = fas->previous;
 78:   prevfas  = (SNES_FAS*)prevsnes->data;
 79:   /* interpolate down the solution */
 80:   MatInterpolate(prevfas->interpolate, X, prevfas->Xg);
 81:   /* the RHS we care about is at the coarsest level */
 82:   b_temp            = prevsnes->vec_rhs;
 83:   prevsnes->vec_rhs = NULL;
 84:   SNESComputeFunction(prevsnes, prevfas->Xg, prevfas->Fg);
 85:   prevsnes->vec_rhs = b_temp;
 86:   /* restrict up the function */
 87:   MatRestrict(prevfas->restrct, prevfas->Fg, F);
 88:   return(0);
 89: }