Actual source code: fasgalerkin.c

      1: #include <../src/snes/impls/fas/fasimpls.h>

      3: /*@
      4:    SNESFASGetGalerkin - Gets if the coarse problems are formed by projection to the fine problem

      6:    Input Parameter:
      7: .  snes - the nonlinear solver context

      9:    Output parameter:
     10: .  flg - the status of the galerkin problem

     12:    Level: advanced

     14: .seealso: SNESFASSetLevels(), SNESFASSetGalerkin()
     15: @*/
     16: PetscErrorCode SNESFASGetGalerkin(SNES snes, PetscBool *flg)
     17: {
     18:   SNES_FAS *fas;

     22:   fas = (SNES_FAS*)snes->data;
     23:   *flg = fas->galerkin;
     24:   return(0);
     25: }

     27: /*@
     28:    SNESFASSetGalerkin - Sets coarse problems as formed by projection to the fine problem

     30:    Input Parameter:
     31: +  snes - the nonlinear solver context
     32: -  flg - the status of the galerkin problem

     34:    Level: advanced

     36: .seealso: SNESFASSetLevels(), SNESFASGetGalerkin()
     37: @*/
     38: PetscErrorCode SNESFASSetGalerkin(SNES snes, PetscBool flg)
     39: {
     40:   SNES_FAS       *fas;

     45:   fas = (SNES_FAS*)snes->data;
     46:   fas->galerkin = flg;
     47:   if (fas->next) {SNESFASSetGalerkin(fas->next, flg);}
     48:   return(0);
     49: }

     51: /*@C
     52:    SNESFASGalerkinFunctionDefault - Computes the Galerkin FAS function

     54:    Input Parameters:
     55: +  snes - the nonlinear solver context
     56: .  X - input vector
     57: -  ctx - the FAS context

     59:    Output Parameter:
     60: .  F - output vector

     62:    Notes:
     63:    The Galerkin FAS function evalutation is defined as
     64: $  F^l(x^l) = I^l_0 F^0(P^0_l x^l)

     66:    Level: developer

     68: .seealso: SNESFASGetGalerkin(), SNESFASSetGalerkin()
     69: @*/
     70: PetscErrorCode SNESFASGalerkinFunctionDefault(SNES snes, Vec X, Vec F, void *ctx)
     71: {
     72:   SNES           fassnes;
     73:   SNES_FAS       *fas;
     74:   SNES_FAS       *prevfas;
     75:   SNES           prevsnes;
     76:   Vec            b_temp;

     80:   /* prolong to the fine level and evaluate there. */
     81:   fassnes  = (SNES)ctx;
     82:   fas      = (SNES_FAS*)fassnes->data;
     83:   prevsnes = fas->previous;
     84:   prevfas  = (SNES_FAS*)prevsnes->data;
     85:   /* interpolate down the solution */
     86:   MatInterpolate(prevfas->interpolate, X, prevfas->Xg);
     87:   /* the RHS we care about is at the coarsest level */
     88:   b_temp            = prevsnes->vec_rhs;
     89:   prevsnes->vec_rhs = NULL;
     90:   SNESComputeFunction(prevsnes, prevfas->Xg, prevfas->Fg);
     91:   prevsnes->vec_rhs = b_temp;
     92:   /* restrict up the function */
     93:   MatRestrict(prevfas->restrct, prevfas->Fg, F);
     94:   return(0);
     95: }