Actual source code: vi.c

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

      4: /*@C
      5:    SNESVISetComputeVariableBounds - Sets a function that is called to compute the variable bounds

      7:    Input parameter:
      8: +  snes - the SNES context
      9: -  compute - computes the bounds

     11:    Level: advanced

     13: .seealso:   SNESVISetVariableBounds()

     15: @*/
     16: PetscErrorCode SNESVISetComputeVariableBounds(SNES snes, PetscErrorCode (*compute)(SNES,Vec,Vec))
     17: {
     18:   PetscErrorCode ierr,(*f)(SNES,PetscErrorCode (*)(SNES,Vec,Vec));

     22:   PetscObjectQueryFunction((PetscObject)snes,"SNESVISetComputeVariableBounds_C",&f);
     23:   if (!f) {
     24:     SNESVISetComputeVariableBounds_VI(snes,compute);
     25:   } else {
     26:     PetscUseMethod(snes,"SNESVISetComputeVariableBounds_C",(SNES,PetscErrorCode (*)(SNES,Vec,Vec)),(snes,compute));
     27:   }
     28:   return(0);
     29: }

     31: PetscErrorCode SNESVISetComputeVariableBounds_VI(SNES snes,SNESVIComputeVariableBoundsFunction compute)
     32: {
     34:   snes->ops->computevariablebounds = compute;
     35:   return(0);
     36: }

     38: /* --------------------------------------------------------------------------------------------------------*/

     40: PetscErrorCode  SNESVIMonitorResidual(SNES snes,PetscInt its,PetscReal fgnorm,void *dummy)
     41: {
     43:   Vec            X, F, Finactive;
     44:   IS             isactive;
     45:   PetscViewer    viewer = (PetscViewer) dummy;

     48:   SNESGetFunction(snes,&F,NULL,NULL);
     49:   SNESGetSolution(snes,&X);
     50:   SNESVIGetActiveSetIS(snes,X,F,&isactive);
     51:   VecDuplicate(F,&Finactive);
     52:   VecCopy(F,Finactive);
     53:   VecISSet(Finactive,isactive,0.0);
     54:   ISDestroy(&isactive);
     55:   VecView(Finactive,viewer);
     56:   VecDestroy(&Finactive);
     57:   return(0);
     58: }

     60: PetscErrorCode  SNESMonitorVI(SNES snes,PetscInt its,PetscReal fgnorm,void *dummy)
     61: {
     62:   PetscErrorCode    ierr;
     63:   PetscViewer       viewer = (PetscViewer) dummy;
     64:   const PetscScalar *x,*xl,*xu,*f;
     65:   PetscInt          i,n,act[2] = {0,0},fact[2],N;
     66:   /* Number of components that actually hit the bounds (c.f. active variables) */
     67:   PetscInt          act_bound[2] = {0,0},fact_bound[2];
     68:   PetscReal         rnorm,fnorm,zerotolerance = snes->vizerotolerance;
     69:   double            tmp;

     73:   VecGetLocalSize(snes->vec_sol,&n);
     74:   VecGetSize(snes->vec_sol,&N);
     75:   VecGetArrayRead(snes->xl,&xl);
     76:   VecGetArrayRead(snes->xu,&xu);
     77:   VecGetArrayRead(snes->vec_sol,&x);
     78:   VecGetArrayRead(snes->vec_func,&f);

     80:   rnorm = 0.0;
     81:   for (i=0; i<n; i++) {
     82:     if (((PetscRealPart(x[i]) > PetscRealPart(xl[i]) + zerotolerance || (PetscRealPart(f[i]) <= 0.0)) && ((PetscRealPart(x[i]) < PetscRealPart(xu[i]) - zerotolerance) || PetscRealPart(f[i]) >= 0.0))) rnorm += PetscRealPart(PetscConj(f[i])*f[i]);
     83:     else if (PetscRealPart(x[i]) <= PetscRealPart(xl[i]) + zerotolerance && PetscRealPart(f[i]) > 0.0) act[0]++;
     84:     else if (PetscRealPart(x[i]) >= PetscRealPart(xu[i]) - zerotolerance && PetscRealPart(f[i]) < 0.0) act[1]++;
     85:     else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"Can never get here");
     86:   }

     88:   for (i=0; i<n; i++) {
     89:     if (PetscRealPart(x[i]) <= PetscRealPart(xl[i]) + zerotolerance) act_bound[0]++;
     90:     else if (PetscRealPart(x[i]) >= PetscRealPart(xu[i]) - zerotolerance) act_bound[1]++;
     91:   }
     92:   VecRestoreArrayRead(snes->vec_func,&f);
     93:   VecRestoreArrayRead(snes->xl,&xl);
     94:   VecRestoreArrayRead(snes->xu,&xu);
     95:   VecRestoreArrayRead(snes->vec_sol,&x);
     96:   MPIU_Allreduce(&rnorm,&fnorm,1,MPIU_REAL,MPIU_SUM,PetscObjectComm((PetscObject)snes));
     97:   MPIU_Allreduce(act,fact,2,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)snes));
     98:   MPIU_Allreduce(act_bound,fact_bound,2,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)snes));
     99:   fnorm = PetscSqrtReal(fnorm);

    101:   PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);
    102:   if (snes->ntruebounds) tmp = ((double)(fact[0]+fact[1]))/((double)snes->ntruebounds);
    103:   else tmp = 0.0;
    104:   PetscViewerASCIIPrintf(viewer,"%3D SNES VI Function norm %g Active lower constraints %D/%D upper constraints %D/%D Percent of total %g Percent of bounded %g\n",its,(double)fnorm,fact[0],fact_bound[0],fact[1],fact_bound[1],((double)(fact[0]+fact[1]))/((double)N),tmp);

    106:   PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);
    107:   return(0);
    108: }

    110: /*
    111:      Checks if J^T F = 0 which implies we've found a local minimum of the norm of the function,
    112:     || F(u) ||_2 but not a zero, F(u) = 0. In the case when one cannot compute J^T F we use the fact that
    113:     0 = (J^T F)^T W = F^T J W iff W not in the null space of J. Thanks for Jorge More
    114:     for this trick. One assumes that the probability that W is in the null space of J is very, very small.
    115: */
    116: PetscErrorCode SNESVICheckLocalMin_Private(SNES snes,Mat A,Vec F,Vec W,PetscReal fnorm,PetscBool *ismin)
    117: {
    118:   PetscReal      a1;
    120:   PetscBool      hastranspose;

    123:   *ismin = PETSC_FALSE;
    124:   MatHasOperation(A,MATOP_MULT_TRANSPOSE,&hastranspose);
    125:   if (hastranspose) {
    126:     /* Compute || J^T F|| */
    127:     MatMultTranspose(A,F,W);
    128:     VecNorm(W,NORM_2,&a1);
    129:     PetscInfo1(snes,"|| J^T F|| %g near zero implies found a local minimum\n",(double)(a1/fnorm));
    130:     if (a1/fnorm < 1.e-4) *ismin = PETSC_TRUE;
    131:   } else {
    132:     Vec         work;
    133:     PetscScalar result;
    134:     PetscReal   wnorm;

    136:     VecSetRandom(W,NULL);
    137:     VecNorm(W,NORM_2,&wnorm);
    138:     VecDuplicate(W,&work);
    139:     MatMult(A,W,work);
    140:     VecDot(F,work,&result);
    141:     VecDestroy(&work);
    142:     a1   = PetscAbsScalar(result)/(fnorm*wnorm);
    143:     PetscInfo1(snes,"(F^T J random)/(|| F ||*||random|| %g near zero implies found a local minimum\n",(double)a1);
    144:     if (a1 < 1.e-4) *ismin = PETSC_TRUE;
    145:   }
    146:   return(0);
    147: }

    149: /*
    150:      Checks if J^T(F - J*X) = 0
    151: */
    152: PetscErrorCode SNESVICheckResidual_Private(SNES snes,Mat A,Vec F,Vec X,Vec W1,Vec W2)
    153: {
    154:   PetscReal      a1,a2;
    156:   PetscBool      hastranspose;

    159:   MatHasOperation(A,MATOP_MULT_TRANSPOSE,&hastranspose);
    160:   if (hastranspose) {
    161:     MatMult(A,X,W1);
    162:     VecAXPY(W1,-1.0,F);

    164:     /* Compute || J^T W|| */
    165:     MatMultTranspose(A,W1,W2);
    166:     VecNorm(W1,NORM_2,&a1);
    167:     VecNorm(W2,NORM_2,&a2);
    168:     if (a1 != 0.0) {
    169:       PetscInfo1(snes,"||J^T(F-Ax)||/||F-AX|| %g near zero implies inconsistent rhs\n",(double)(a2/a1));
    170:     }
    171:   }
    172:   return(0);
    173: }

    175: /*
    176:   SNESConvergedDefault_VI - Checks the convergence of the semismooth newton algorithm.

    178:   Notes:
    179:   The convergence criterion currently implemented is
    180:   merit < abstol
    181:   merit < rtol*merit_initial
    182: */
    183: PetscErrorCode SNESConvergedDefault_VI(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gradnorm,PetscReal fnorm,SNESConvergedReason *reason,void *dummy)
    184: {

    191:   *reason = SNES_CONVERGED_ITERATING;

    193:   if (!it) {
    194:     /* set parameter for default relative tolerance convergence test */
    195:     snes->ttol = fnorm*snes->rtol;
    196:   }
    197:   if (fnorm != fnorm) {
    198:     PetscInfo(snes,"Failed to converged, function norm is NaN\n");
    199:     *reason = SNES_DIVERGED_FNORM_NAN;
    200:   } else if (fnorm < snes->abstol && (it || !snes->forceiteration)) {
    201:     PetscInfo2(snes,"Converged due to function norm %g < %g\n",(double)fnorm,(double)snes->abstol);
    202:     *reason = SNES_CONVERGED_FNORM_ABS;
    203:   } else if (snes->nfuncs >= snes->max_funcs && snes->max_funcs >= 0) {
    204:     PetscInfo2(snes,"Exceeded maximum number of function evaluations: %D > %D\n",snes->nfuncs,snes->max_funcs);
    205:     *reason = SNES_DIVERGED_FUNCTION_COUNT;
    206:   }

    208:   if (it && !*reason) {
    209:     if (fnorm < snes->ttol) {
    210:       PetscInfo2(snes,"Converged due to function norm %g < %g (relative tolerance)\n",(double)fnorm,(double)snes->ttol);
    211:       *reason = SNES_CONVERGED_FNORM_RELATIVE;
    212:     }
    213:   }
    214:   return(0);
    215: }

    218: /* -------------------------------------------------------------------------- */
    219: /*
    220:    SNESVIProjectOntoBounds - Projects X onto the feasible region so that Xl[i] <= X[i] <= Xu[i] for i = 1...n.

    222:    Input Parameters:
    223: .  SNES - nonlinear solver context

    225:    Output Parameters:
    226: .  X - Bound projected X

    228: */

    230: PetscErrorCode SNESVIProjectOntoBounds(SNES snes,Vec X)
    231: {
    232:   PetscErrorCode    ierr;
    233:   const PetscScalar *xl,*xu;
    234:   PetscScalar       *x;
    235:   PetscInt          i,n;

    238:   VecGetLocalSize(X,&n);
    239:   VecGetArray(X,&x);
    240:   VecGetArrayRead(snes->xl,&xl);
    241:   VecGetArrayRead(snes->xu,&xu);

    243:   for (i = 0; i<n; i++) {
    244:     if (PetscRealPart(x[i]) < PetscRealPart(xl[i])) x[i] = xl[i];
    245:     else if (PetscRealPart(x[i]) > PetscRealPart(xu[i])) x[i] = xu[i];
    246:   }
    247:   VecRestoreArray(X,&x);
    248:   VecRestoreArrayRead(snes->xl,&xl);
    249:   VecRestoreArrayRead(snes->xu,&xu);
    250:   return(0);
    251: }

    254: /*
    255:    SNESVIGetActiveSetIndices - Gets the global indices for the active set variables

    257:    Input parameter:
    258: .  snes - the SNES context
    259: .  X    - the snes solution vector
    260: .  F    - the nonlinear function vector

    262:    Output parameter:
    263: .  ISact - active set index set
    264:  */
    265: PetscErrorCode SNESVIGetActiveSetIS(SNES snes,Vec X,Vec F,IS *ISact)
    266: {
    267:   PetscErrorCode    ierr;
    268:   Vec               Xl=snes->xl,Xu=snes->xu;
    269:   const PetscScalar *x,*f,*xl,*xu;
    270:   PetscInt          *idx_act,i,nlocal,nloc_isact=0,ilow,ihigh,i1=0;
    271:   PetscReal         zerotolerance = snes->vizerotolerance;

    274:   VecGetLocalSize(X,&nlocal);
    275:   VecGetOwnershipRange(X,&ilow,&ihigh);
    276:   VecGetArrayRead(X,&x);
    277:   VecGetArrayRead(Xl,&xl);
    278:   VecGetArrayRead(Xu,&xu);
    279:   VecGetArrayRead(F,&f);
    280:   /* Compute active set size */
    281:   for (i=0; i < nlocal;i++) {
    282:     if (!((PetscRealPart(x[i]) > PetscRealPart(xl[i]) + zerotolerance || (PetscRealPart(f[i]) <= 0.0)) && ((PetscRealPart(x[i]) < PetscRealPart(xu[i]) - zerotolerance) || PetscRealPart(f[i]) >= 0.0))) nloc_isact++;
    283:   }

    285:   PetscMalloc1(nloc_isact,&idx_act);

    287:   /* Set active set indices */
    288:   for (i=0; i < nlocal; i++) {
    289:     if (!((PetscRealPart(x[i]) > PetscRealPart(xl[i]) + zerotolerance || (PetscRealPart(f[i]) <= 0.0)) && ((PetscRealPart(x[i]) < PetscRealPart(xu[i]) - zerotolerance) || PetscRealPart(f[i]) >= 0.0))) idx_act[i1++] = ilow+i;
    290:   }

    292:   /* Create active set IS */
    293:   ISCreateGeneral(PetscObjectComm((PetscObject)snes),nloc_isact,idx_act,PETSC_OWN_POINTER,ISact);

    295:   VecRestoreArrayRead(X,&x);
    296:   VecRestoreArrayRead(Xl,&xl);
    297:   VecRestoreArrayRead(Xu,&xu);
    298:   VecRestoreArrayRead(F,&f);
    299:   return(0);
    300: }

    302: PetscErrorCode SNESVICreateIndexSets_RS(SNES snes,Vec X,Vec F,IS *ISact,IS *ISinact)
    303: {
    305:   PetscInt       rstart,rend;

    308:   SNESVIGetActiveSetIS(snes,X,F,ISact);
    309:   VecGetOwnershipRange(X,&rstart,&rend);
    310:   ISComplement(*ISact,rstart,rend,ISinact);
    311:   return(0);
    312: }

    314: PetscErrorCode SNESVIComputeInactiveSetFnorm(SNES snes,Vec F,Vec X, PetscReal *fnorm)
    315: {
    316:   PetscErrorCode    ierr;
    317:   const PetscScalar *x,*xl,*xu,*f;
    318:   PetscInt          i,n;
    319:   PetscReal         rnorm,zerotolerance = snes->vizerotolerance;

    322:   VecGetLocalSize(X,&n);
    323:   VecGetArrayRead(snes->xl,&xl);
    324:   VecGetArrayRead(snes->xu,&xu);
    325:   VecGetArrayRead(X,&x);
    326:   VecGetArrayRead(F,&f);
    327:   rnorm = 0.0;
    328:   for (i=0; i<n; i++) {
    329:     if (((PetscRealPart(x[i]) > PetscRealPart(xl[i]) + zerotolerance || (PetscRealPart(f[i]) <= 0.0)) && ((PetscRealPart(x[i]) < PetscRealPart(xu[i]) - zerotolerance) || PetscRealPart(f[i]) >= 0.0))) rnorm += PetscRealPart(PetscConj(f[i])*f[i]);
    330:   }
    331:   VecRestoreArrayRead(F,&f);
    332:   VecRestoreArrayRead(snes->xl,&xl);
    333:   VecRestoreArrayRead(snes->xu,&xu);
    334:   VecRestoreArrayRead(X,&x);
    335:   MPIU_Allreduce(&rnorm,fnorm,1,MPIU_REAL,MPIU_SUM,PetscObjectComm((PetscObject)snes));
    336:   *fnorm = PetscSqrtReal(*fnorm);
    337:   return(0);
    338: }

    340: PetscErrorCode SNESVIDMComputeVariableBounds(SNES snes,Vec xl, Vec xu)
    341: {

    345:   DMComputeVariableBounds(snes->dm, xl, xu);
    346:   return(0);
    347: }

    350: /* -------------------------------------------------------------------------- */
    351: /*
    352:    SNESSetUp_VI - Does setup common to all VI solvers -- basically makes sure bounds have been properly set up
    353:    of the SNESVI nonlinear solver.

    355:    Input Parameter:
    356: .  snes - the SNES context

    358:    Application Interface Routine: SNESSetUp()

    360:    Notes:
    361:    For basic use of the SNES solvers, the user need not explicitly call
    362:    SNESSetUp(), since these actions will automatically occur during
    363:    the call to SNESSolve().
    364:  */
    365: PetscErrorCode SNESSetUp_VI(SNES snes)
    366: {
    368:   PetscInt       i_start[3],i_end[3];

    371:   SNESSetWorkVecs(snes,1);
    372:   SNESSetUpMatrices(snes);

    374:   if (!snes->ops->computevariablebounds && snes->dm) {
    375:     PetscBool flag;
    376:     DMHasVariableBounds(snes->dm, &flag);
    377:     if (flag) {
    378:       snes->ops->computevariablebounds = SNESVIDMComputeVariableBounds;
    379:     }
    380:   }
    381:   if (!snes->usersetbounds) {
    382:     if (snes->ops->computevariablebounds) {
    383:       if (!snes->xl) {VecDuplicate(snes->vec_sol,&snes->xl);}
    384:       if (!snes->xu) {VecDuplicate(snes->vec_sol,&snes->xu);}
    385:       (*snes->ops->computevariablebounds)(snes,snes->xl,snes->xu);
    386:     } else if (!snes->xl && !snes->xu) {
    387:       /* If the lower and upper bound on variables are not set, set it to -Inf and Inf */
    388:       VecDuplicate(snes->vec_sol, &snes->xl);
    389:       VecSet(snes->xl,PETSC_NINFINITY);
    390:       VecDuplicate(snes->vec_sol, &snes->xu);
    391:       VecSet(snes->xu,PETSC_INFINITY);
    392:     } else {
    393:       /* Check if lower bound, upper bound and solution vector distribution across the processors is identical */
    394:       VecGetOwnershipRange(snes->vec_sol,i_start,i_end);
    395:       VecGetOwnershipRange(snes->xl,i_start+1,i_end+1);
    396:       VecGetOwnershipRange(snes->xu,i_start+2,i_end+2);
    397:       if ((i_start[0] != i_start[1]) || (i_start[0] != i_start[2]) || (i_end[0] != i_end[1]) || (i_end[0] != i_end[2]))
    398:         SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Distribution of lower bound, upper bound and the solution vector should be identical across all the processors.");
    399:     }
    400:   }
    401:   return(0);
    402: }
    403: /* -------------------------------------------------------------------------- */
    404: PetscErrorCode SNESReset_VI(SNES snes)
    405: {

    409:   VecDestroy(&snes->xl);
    410:   VecDestroy(&snes->xu);
    411:   snes->usersetbounds = PETSC_FALSE;
    412:   return(0);
    413: }

    415: /*
    416:    SNESDestroy_VI - Destroys the private SNES_VI context that was created
    417:    with SNESCreate_VI().

    419:    Input Parameter:
    420: .  snes - the SNES context

    422:    Application Interface Routine: SNESDestroy()
    423:  */
    424: PetscErrorCode SNESDestroy_VI(SNES snes)
    425: {

    429:   PetscFree(snes->data);

    431:   /* clear composed functions */
    432:   PetscObjectComposeFunction((PetscObject)snes,"SNESLineSearchSet_C",NULL);
    433:   PetscObjectComposeFunction((PetscObject)snes,"SNESLineSearchSetDefaultMonitor_C",NULL);
    434:   return(0);
    435: }

    437: /*@
    438:    SNESVISetVariableBounds - Sets the lower and upper bounds for the solution vector. xl <= x <= xu.

    440:    Input Parameters:
    441: +  snes - the SNES context.
    442: .  xl   - lower bound.
    443: -  xu   - upper bound.

    445:    Notes:
    446:    If this routine is not called then the lower and upper bounds are set to
    447:    PETSC_NINFINITY and PETSC_INFINITY respectively during SNESSetUp().

    449:    Level: advanced

    451: @*/
    452: PetscErrorCode SNESVISetVariableBounds(SNES snes, Vec xl, Vec xu)
    453: {
    454:   PetscErrorCode ierr,(*f)(SNES,Vec,Vec);

    460:   PetscObjectQueryFunction((PetscObject)snes,"SNESVISetVariableBounds_C",&f);
    461:   if (!f) {
    462:     SNESVISetVariableBounds_VI(snes, xl, xu);
    463:   } else {
    464:     PetscUseMethod(snes,"SNESVISetVariableBounds_C",(SNES,Vec,Vec),(snes,xl,xu));
    465:   }
    466:   snes->usersetbounds = PETSC_TRUE;
    467:   return(0);
    468: }

    470: PetscErrorCode SNESVISetVariableBounds_VI(SNES snes,Vec xl,Vec xu)
    471: {
    472:   PetscErrorCode    ierr;
    473:   const PetscScalar *xxl,*xxu;
    474:   PetscInt          i,n, cnt = 0;

    477:   SNESGetFunction(snes,&snes->vec_func,NULL,NULL);
    478:   if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Must call SNESSetFunction() or SNESSetDM() first");
    479:   {
    480:     PetscInt xlN,xuN,N;
    481:     VecGetSize(xl,&xlN);
    482:     VecGetSize(xu,&xuN);
    483:     VecGetSize(snes->vec_func,&N);
    484:     if (xlN != N) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Incompatible vector lengths lower bound = %D solution vector = %D",xlN,N);
    485:     if (xuN != N) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Incompatible vector lengths: upper bound = %D solution vector = %D",xuN,N);
    486:   }
    487:   PetscObjectReference((PetscObject)xl);
    488:   PetscObjectReference((PetscObject)xu);
    489:   VecDestroy(&snes->xl);
    490:   VecDestroy(&snes->xu);
    491:   snes->xl = xl;
    492:   snes->xu = xu;
    493:   VecGetLocalSize(xl,&n);
    494:   VecGetArrayRead(xl,&xxl);
    495:   VecGetArrayRead(xu,&xxu);
    496:   for (i=0; i<n; i++) cnt += ((xxl[i] != PETSC_NINFINITY) || (xxu[i] != PETSC_INFINITY));

    498:   MPIU_Allreduce(&cnt,&snes->ntruebounds,1,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)snes));
    499:   VecRestoreArrayRead(xl,&xxl);
    500:   VecRestoreArrayRead(xu,&xxu);
    501:   return(0);
    502: }

    504: PetscErrorCode SNESSetFromOptions_VI(PetscOptionItems *PetscOptionsObject,SNES snes)
    505: {
    507:   PetscBool      flg = PETSC_FALSE;

    510:   PetscOptionsHead(PetscOptionsObject,"SNES VI options");
    511:   PetscOptionsReal("-snes_vi_zero_tolerance","Tolerance for considering x[] value to be on a bound","None",snes->vizerotolerance,&snes->vizerotolerance,NULL);
    512:   PetscOptionsBool("-snes_vi_monitor","Monitor all non-active variables","SNESMonitorResidual",flg,&flg,NULL);
    513:   if (flg) {
    514:     SNESMonitorSet(snes,SNESMonitorVI,PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)),NULL);
    515:   }
    516:   flg = PETSC_FALSE;
    517:   PetscOptionsBool("-snes_vi_monitor_residual","Monitor residual all non-active variables; using zero for active constraints","SNESMonitorVIResidual",flg,&flg,NULL);
    518:   if (flg) {
    519:     SNESMonitorSet(snes,SNESVIMonitorResidual,PETSC_VIEWER_DRAW_(PetscObjectComm((PetscObject)snes)),NULL);
    520:   }
    521:   PetscOptionsTail();
    522:   return(0);
    523: }