Date: 2015-10-02T22:23:39+00:00

Actual source code: snespc.c
petsc-3.6.2 2015-10-02
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      2: #include <petsc/private/snesimpl.h>      /*I "petscsnes.h"  I*/
      3: #include <petscdmshell.h>

      8: /*@
      9:    SNESApplyNPC - Calls SNESSolve() on preconditioner for the SNES

     11:    Collective on SNES

     13:    Input Parameters:
     14: +  snes - the SNES context
     15: .  x - input vector
     16: -  f - optional; the function evaluation on x

     18:    Output Parameter:
     19: .  y - function vector, as set by SNESSetFunction()

     21:    Notes:
     22:    SNESComputeFunction() should be called on x before SNESApplyNPC() is called, as it is
     23:    with SNESComuteJacobian().

     25:    Level: developer

     27: .keywords: SNES, nonlinear, compute, function

     29: .seealso: SNESGetNPC(),SNESSetNPC(),SNESComputeFunction()
     30: @*/
     31: PetscErrorCode  SNESApplyNPC(SNES snes,Vec x,Vec f,Vec y)
     32: {

     41:   VecValidValues(x,2,PETSC_TRUE);
     42:   if (snes->pc) {
     43:     if (f) {
     44:       SNESSetInitialFunction(snes->pc,f);
     45:     }
     46:     VecCopy(x,y);
     47:     PetscLogEventBegin(SNES_NPCSolve,snes->pc,x,y,0);
     48:     SNESSolve(snes->pc,snes->vec_rhs,y);
     49:     PetscLogEventEnd(SNES_NPCSolve,snes->pc,x,y,0);
     50:     VecAYPX(y,-1.0,x);
     51:     return(0);
     52:   }
     53:   return(0);
     54: }

     58: PetscErrorCode SNESComputeFunctionDefaultNPC(SNES snes,Vec X,Vec F)
     59: {
     60: /* This is to be used as an argument to SNESMF -- NOT as a "function" */
     61:   SNESConvergedReason reason;
     62:   PetscErrorCode      ierr;

     65:   if (snes->pc) {
     66:     SNESApplyNPC(snes,X,NULL,F);
     67:     SNESGetConvergedReason(snes->pc,&reason);
     68:     if (reason < 0  && reason != SNES_DIVERGED_MAX_IT) {
     69:       SNESSetFunctionDomainError(snes);
     70:     }
     71:   } else {
     72:     SNESComputeFunction(snes,X,F);
     73:   }
     74:   return(0);
     75: }

     79: /*@
     80:    SNESGetNPCFunction - Gets the function from a preconditioner after SNESSolve() has been called.

     82:    Collective on SNES

     84:    Input Parameters:
     85: .  snes - the SNES context

     87:    Output Parameter:
     88: .  F - function vector
     89: .  fnorm - the norm of F

     91:    Level: developer

     93: .keywords: SNES, nonlinear, function

     95: .seealso: SNESGetNPC(),SNESSetNPC(),SNESComputeFunction(),SNESApplyNPC(),SNESSolve()
     96: @*/
     97: PetscErrorCode SNESGetNPCFunction(SNES snes,Vec F,PetscReal *fnorm)
     98: {
     99:   PetscErrorCode   ierr;
    100:   PCSide           npcside;
    101:   SNESFunctionType functype;
    102:   SNESNormSchedule normschedule;
    103:   Vec              FPC,XPC;

    106:   if (snes->pc) {
    107:     SNESGetNPCSide(snes->pc,&npcside);
    108:     SNESGetFunctionType(snes->pc,&functype);
    109:     SNESGetNormSchedule(snes->pc,&normschedule);

    111:     /* check if the function is valid based upon how the inner solver is preconditioned */
    112:     if (normschedule != SNES_NORM_NONE && normschedule != SNES_NORM_INITIAL_ONLY && (npcside == PC_RIGHT || functype == SNES_FUNCTION_UNPRECONDITIONED)) {
    113:       SNESGetFunction(snes->pc,&FPC,NULL,NULL);
    114:       if (FPC) {
    115:         if (fnorm) {VecNorm(FPC,NORM_2,fnorm);}
    116:         VecCopy(FPC,F);
    117:       } else {
    118:         SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Preconditioner has no function");
    119:       }
    120:     } else {
    121:       SNESGetSolution(snes->pc,&XPC);
    122:       if (XPC) {
    123:         SNESComputeFunction(snes->pc,XPC,F);
    124:         if (fnorm) {VecNorm(F,NORM_2,fnorm);}
    125:       } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Preconditioner has no solution");
    126:     }
    127:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No preconditioner set");
    128:   return(0);
    129: }