Example #1
0
void Flow::addFlowStats(bool cli2srv_direction, u_int in_pkts, u_int in_bytes,
			u_int out_pkts, u_int out_bytes, time_t last_seen) {
  updateSeen(last_seen);

  if (cli2srv_direction)
    cli2srv_packets += in_pkts, cli2srv_bytes += in_bytes, srv2cli_packets += out_pkts, srv2cli_bytes += out_bytes;
  else
    cli2srv_packets += out_pkts, cli2srv_bytes += out_bytes, srv2cli_packets += in_pkts, srv2cli_bytes += in_bytes;

  updateActivities();
}
Example #2
0
// step overwrite for ICO
void ICO::step(){
  updateActivities();
  updateOutputs();
  updateWeights();
}
Example #3
0
ActivityListModel::ActivityListModel(const SoundStorage *storage, QObject *parent)
                  : ListModelBase(storage,parent) {
    connect(soundStorage, SIGNAL(activitiesUpdated(QList<QPair<int,QString> >)),
            this, SLOT(updateActivities(QList<QPair<int,QString> >)));
}
Example #4
0
/** execution method of primal heuristic */
static
SCIP_DECL_HEUREXEC(heurExecShifting) /*lint --e{715}*/
{   /*lint --e{715}*/
    SCIP_HEURDATA* heurdata;
    SCIP_SOL* sol;
    SCIP_VAR** lpcands;
    SCIP_Real* lpcandssol;
    SCIP_ROW** lprows;
    SCIP_Real* activities;
    SCIP_ROW** violrows;
    SCIP_Real* nincreases;
    SCIP_Real* ndecreases;
    int* violrowpos;
    int* nfracsinrow;
    SCIP_Real increaseweight;
    SCIP_Real obj;
    SCIP_Real bestshiftval;
    SCIP_Real minobj;
    int nlpcands;
    int nlprows;
    int nvars;
    int nfrac;
    int nviolrows;
    int nprevviolrows;
    int minnviolrows;
    int nnonimprovingshifts;
    int c;
    int r;
    SCIP_Longint nlps;
    SCIP_Longint ncalls;
    SCIP_Longint nsolsfound;
    SCIP_Longint nnodes;

    assert(strcmp(SCIPheurGetName(heur), HEUR_NAME) == 0);
    assert(scip != NULL);
    assert(result != NULL);
    assert(SCIPhasCurrentNodeLP(scip));

    *result = SCIP_DIDNOTRUN;

    /* only call heuristic, if an optimal LP solution is at hand */
    if( SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
        return SCIP_OKAY;

    /* only call heuristic, if the LP objective value is smaller than the cutoff bound */
    if( SCIPisGE(scip, SCIPgetLPObjval(scip), SCIPgetCutoffbound(scip)) )
        return SCIP_OKAY;

    /* get heuristic data */
    heurdata = SCIPheurGetData(heur);
    assert(heurdata != NULL);

    /* don't call heuristic, if we have already processed the current LP solution */
    nlps = SCIPgetNLPs(scip);
    if( nlps == heurdata->lastlp )
        return SCIP_OKAY;
    heurdata->lastlp = nlps;

    /* don't call heuristic, if it was not successful enough in the past */
    ncalls = SCIPheurGetNCalls(heur);
    nsolsfound = 10*SCIPheurGetNBestSolsFound(heur) + SCIPheurGetNSolsFound(heur);
    nnodes = SCIPgetNNodes(scip);
    if( nnodes % ((ncalls/100)/(nsolsfound+1)+1) != 0 )
        return SCIP_OKAY;

    /* get fractional variables, that should be integral */
    /* todo check if heuristic should include implicit integer variables for its calculations */
    SCIP_CALL( SCIPgetLPBranchCands(scip, &lpcands, &lpcandssol, NULL, &nlpcands, NULL, NULL) );
    nfrac = nlpcands;

    /* only call heuristic, if LP solution is fractional */
    if( nfrac == 0 )
        return SCIP_OKAY;

    *result = SCIP_DIDNOTFIND;

    /* get LP rows */
    SCIP_CALL( SCIPgetLPRowsData(scip, &lprows, &nlprows) );

    SCIPdebugMessage("executing shifting heuristic: %d LP rows, %d fractionals\n", nlprows, nfrac);

    /* get memory for activities, violated rows, and row violation positions */
    nvars = SCIPgetNVars(scip);
    SCIP_CALL( SCIPallocBufferArray(scip, &activities, nlprows) );
    SCIP_CALL( SCIPallocBufferArray(scip, &violrows, nlprows) );
    SCIP_CALL( SCIPallocBufferArray(scip, &violrowpos, nlprows) );
    SCIP_CALL( SCIPallocBufferArray(scip, &nfracsinrow, nlprows) );
    SCIP_CALL( SCIPallocBufferArray(scip, &nincreases, nvars) );
    SCIP_CALL( SCIPallocBufferArray(scip, &ndecreases, nvars) );
    BMSclearMemoryArray(nfracsinrow, nlprows);
    BMSclearMemoryArray(nincreases, nvars);
    BMSclearMemoryArray(ndecreases, nvars);

    /* get the activities for all globally valid rows;
     * the rows should be feasible, but due to numerical inaccuracies in the LP solver, they can be violated
     */
    nviolrows = 0;
    for( r = 0; r < nlprows; ++r )
    {
        SCIP_ROW* row;

        row = lprows[r];
        assert(SCIProwGetLPPos(row) == r);

        if( !SCIProwIsLocal(row) )
        {
            activities[r] = SCIPgetRowActivity(scip, row);
            if( SCIPisFeasLT(scip, activities[r], SCIProwGetLhs(row))
                    || SCIPisFeasGT(scip, activities[r], SCIProwGetRhs(row)) )
            {
                violrows[nviolrows] = row;
                violrowpos[r] = nviolrows;
                nviolrows++;
            }
            else
                violrowpos[r] = -1;
        }
    }

    /* calc the current number of fractional variables in rows */
    for( c = 0; c < nlpcands; ++c )
        addFracCounter(nfracsinrow, nlprows, lpcands[c], +1);

    /* get the working solution from heuristic's local data */
    sol = heurdata->sol;
    assert(sol != NULL);

    /* copy the current LP solution to the working solution */
    SCIP_CALL( SCIPlinkLPSol(scip, sol) );

    /* calculate the minimal objective value possible after rounding fractional variables */
    minobj = SCIPgetSolTransObj(scip, sol);
    assert(minobj < SCIPgetCutoffbound(scip));
    for( c = 0; c < nlpcands; ++c )
    {
        obj = SCIPvarGetObj(lpcands[c]);
        bestshiftval = obj > 0.0 ? SCIPfeasFloor(scip, lpcandssol[c]) : SCIPfeasCeil(scip, lpcandssol[c]);
        minobj += obj * (bestshiftval - lpcandssol[c]);
    }

    /* try to shift remaining variables in order to become/stay feasible */
    nnonimprovingshifts = 0;
    minnviolrows = INT_MAX;
    increaseweight = 1.0;
    while( (nfrac > 0 || nviolrows > 0) && nnonimprovingshifts < MAXSHIFTINGS )
    {
        SCIP_VAR* shiftvar;
        SCIP_Real oldsolval;
        SCIP_Real newsolval;
        SCIP_Bool oldsolvalisfrac;
        int probindex;

        SCIPdebugMessage("shifting heuristic: nfrac=%d, nviolrows=%d, obj=%g (best possible obj: %g), cutoff=%g\n",
                         nfrac, nviolrows, SCIPgetSolOrigObj(scip, sol), SCIPretransformObj(scip, minobj),
                         SCIPretransformObj(scip, SCIPgetCutoffbound(scip)));

        nprevviolrows = nviolrows;

        /* choose next variable to process:
         *  - if a violated row exists, shift a variable decreasing the violation, that has least impact on other rows
         *  - otherwise, shift a variable, that has strongest devastating impact on rows in opposite direction
         */
        shiftvar = NULL;
        oldsolval = 0.0;
        newsolval = 0.0;
        if( nviolrows > 0 && (nfrac == 0 || nnonimprovingshifts < MAXSHIFTINGS-1) )
        {
            SCIP_ROW* row;
            int rowidx;
            int rowpos;
            int direction;

            rowidx = -1;
            rowpos = -1;
            row = NULL;
            if( nfrac > 0 )
            {
                for( rowidx = nviolrows-1; rowidx >= 0; --rowidx )
                {
                    row = violrows[rowidx];
                    rowpos = SCIProwGetLPPos(row);
                    assert(violrowpos[rowpos] == rowidx);
                    if( nfracsinrow[rowpos] > 0 )
                        break;
                }
            }
            if( rowidx == -1 )
            {
                rowidx = SCIPgetRandomInt(0, nviolrows-1, &heurdata->randseed);
                row = violrows[rowidx];
                rowpos = SCIProwGetLPPos(row);
                assert(0 <= rowpos && rowpos < nlprows);
                assert(violrowpos[rowpos] == rowidx);
                assert(nfracsinrow[rowpos] == 0);
            }
            assert(violrowpos[rowpos] == rowidx);

            SCIPdebugMessage("shifting heuristic: try to fix violated row <%s>: %g <= %g <= %g\n",
                             SCIProwGetName(row), SCIProwGetLhs(row), activities[rowpos], SCIProwGetRhs(row));
            SCIPdebug( SCIP_CALL( SCIPprintRow(scip, row, NULL) ) );

            /* get direction in which activity must be shifted */
            assert(SCIPisFeasLT(scip, activities[rowpos], SCIProwGetLhs(row))
                   || SCIPisFeasGT(scip, activities[rowpos], SCIProwGetRhs(row)));
            direction = SCIPisFeasLT(scip, activities[rowpos], SCIProwGetLhs(row)) ? +1 : -1;

            /* search a variable that can shift the activity in the necessary direction */
            SCIP_CALL( selectShifting(scip, sol, row, activities[rowpos], direction,
                                      nincreases, ndecreases, increaseweight, &shiftvar, &oldsolval, &newsolval) );
        }

        if( shiftvar == NULL && nfrac > 0 )
        {
            SCIPdebugMessage("shifting heuristic: search rounding variable and try to stay feasible\n");
            SCIP_CALL( selectEssentialRounding(scip, sol, minobj, lpcands, nlpcands, &shiftvar, &oldsolval, &newsolval) );
        }

        /* check, whether shifting was possible */
        if( shiftvar == NULL || SCIPisEQ(scip, oldsolval, newsolval) )
        {
            SCIPdebugMessage("shifting heuristic:  -> didn't find a shifting variable\n");
            break;
        }

        SCIPdebugMessage("shifting heuristic:  -> shift var <%s>[%g,%g], type=%d, oldval=%g, newval=%g, obj=%g\n",
                         SCIPvarGetName(shiftvar), SCIPvarGetLbGlobal(shiftvar), SCIPvarGetUbGlobal(shiftvar), SCIPvarGetType(shiftvar),
                         oldsolval, newsolval, SCIPvarGetObj(shiftvar));

        /* update row activities of globally valid rows */
        SCIP_CALL( updateActivities(scip, activities, violrows, violrowpos, &nviolrows, nlprows,
                                    shiftvar, oldsolval, newsolval) );
        if( nviolrows >= nprevviolrows )
            nnonimprovingshifts++;
        else if( nviolrows < minnviolrows )
        {
            minnviolrows = nviolrows;
            nnonimprovingshifts = 0;
        }

        /* store new solution value and decrease fractionality counter */
        SCIP_CALL( SCIPsetSolVal(scip, sol, shiftvar, newsolval) );

        /* update fractionality counter and minimal objective value possible after shifting remaining variables */
        oldsolvalisfrac = !SCIPisFeasIntegral(scip, oldsolval)
                          && (SCIPvarGetType(shiftvar) == SCIP_VARTYPE_BINARY || SCIPvarGetType(shiftvar) == SCIP_VARTYPE_INTEGER);
        obj = SCIPvarGetObj(shiftvar);
        if( (SCIPvarGetType(shiftvar) == SCIP_VARTYPE_BINARY || SCIPvarGetType(shiftvar) == SCIP_VARTYPE_INTEGER)
                && oldsolvalisfrac )
        {
            assert(SCIPisFeasIntegral(scip, newsolval));
            nfrac--;
            nnonimprovingshifts = 0;
            minnviolrows = INT_MAX;
            addFracCounter(nfracsinrow, nlprows, shiftvar, -1);

            /* the rounding was already calculated into the minobj -> update only if rounding in "wrong" direction */
            if( obj > 0.0 && newsolval > oldsolval )
                minobj += obj;
            else if( obj < 0.0 && newsolval < oldsolval )
                minobj -= obj;
        }
        else
        {
            /* update minimal possible objective value */
            minobj += obj * (newsolval - oldsolval);
        }

        /* update increase/decrease arrays */
        if( !oldsolvalisfrac )
        {
            probindex = SCIPvarGetProbindex(shiftvar);
            assert(0 <= probindex && probindex < nvars);
            increaseweight *= WEIGHTFACTOR;
            if( newsolval < oldsolval )
                ndecreases[probindex] += increaseweight;
            else
                nincreases[probindex] += increaseweight;
            if( increaseweight >= 1e+09 )
            {
                int i;

                for( i = 0; i < nvars; ++i )
                {
                    nincreases[i] /= increaseweight;
                    ndecreases[i] /= increaseweight;
                }
                increaseweight = 1.0;
            }
        }

        SCIPdebugMessage("shifting heuristic:  -> nfrac=%d, nviolrows=%d, obj=%g (best possible obj: %g)\n",
                         nfrac, nviolrows, SCIPgetSolOrigObj(scip, sol), SCIPretransformObj(scip, minobj));
    }

    /* check, if the new solution is feasible */
    if( nfrac == 0 && nviolrows == 0 )
    {
        SCIP_Bool stored;

        /* check solution for feasibility, and add it to solution store if possible
         * neither integrality nor feasibility of LP rows has to be checked, because this is already
         * done in the shifting heuristic itself; however, we better check feasibility of LP rows,
         * because of numerical problems with activity updating
         */
        SCIP_CALL( SCIPtrySol(scip, sol, FALSE, FALSE, FALSE, TRUE, &stored) );

        if( stored )
        {
            SCIPdebugMessage("found feasible shifted solution:\n");
            SCIPdebug( SCIP_CALL( SCIPprintSol(scip, sol, NULL, FALSE) ) );
            *result = SCIP_FOUNDSOL;
        }
    }

    /* free memory buffers */
    SCIPfreeBufferArray(scip, &ndecreases);
    SCIPfreeBufferArray(scip, &nincreases);
    SCIPfreeBufferArray(scip, &nfracsinrow);
    SCIPfreeBufferArray(scip, &violrowpos);
    SCIPfreeBufferArray(scip, &violrows);
    SCIPfreeBufferArray(scip, &activities);

    return SCIP_OKAY;
}
Example #5
0
void Solver::recordAllUIPCauses() {
// note:
// variables of lower dl: if seen we dont work with them anymore
// variables of this dl: if seen we incorporate their
// antecedent and set to unseen
	bool seen[num_variables() + 1];
	memset(seen, false, sizeof(bool) * (num_variables() + 1));

	static vector<LiteralID> tmp_clause;
	tmp_clause.clear();

	assertion_level_ = 0;
	uip_clauses_.clear();

	unsigned lit_stack_ofs = literal_stack_.size();
	int DL = stack_.get_decision_level();
	unsigned lits_at_current_dl = 0;

	for (auto l : violated_clause) {
		if (var(l).decision_level == 0 || existsUnitClauseOf(l.var()))
			continue;
		if (var(l).decision_level < DL)
			tmp_clause.push_back(l);
		else
			lits_at_current_dl++;
		literal(l).increaseActivity();
		seen[l.var()] = true;
	}
	unsigned n = 0;
	LiteralID curr_lit;
	while (lits_at_current_dl) {
		assert(lit_stack_ofs != 0);
		curr_lit = literal_stack_[--lit_stack_ofs];

		if (!seen[curr_lit.var()])
			continue;

		seen[curr_lit.var()] = false;

		if (lits_at_current_dl-- == 1) {
			n++;
			if (!hasAntecedent(curr_lit)) {
				// this should be the decision literal when in first branch
				// or it is a literal decided to explore in failed literal testing
				//assert(stack_.TOS_decLit() == curr_lit);
				break;
			}
			// perform UIP stuff
			minimizeAndStoreUIPClause(curr_lit.neg(), tmp_clause, seen);
		}

		assert(hasAntecedent(curr_lit));

		if (getAntecedent(curr_lit).isAClause()) {
			updateActivities(getAntecedent(curr_lit).asCl());
			assert(curr_lit == *beginOf(getAntecedent(curr_lit).asCl()));

			for (auto it = beginOf(getAntecedent(curr_lit).asCl()) + 1;
					*it != SENTINEL_CL; it++) {
				if (seen[it->var()] || var(*it).decision_level == 0
						|| existsUnitClauseOf(it->var()))
					continue;
				if (var(*it).decision_level < DL)
					tmp_clause.push_back(*it);
				else
					lits_at_current_dl++;
				seen[it->var()] = true;
			}
		} else {
			LiteralID alit = getAntecedent(curr_lit).asLit();
			literal(alit).increaseActivity();
			literal(curr_lit).increaseActivity();
			if (!seen[alit.var()] && !var(alit).decision_level == 0
					&& !existsUnitClauseOf(alit.var())) {
				if (var(alit).decision_level < DL)
					tmp_clause.push_back(alit);
				else
					lits_at_current_dl++;
				seen[alit.var()] = true;
			}
		}
	}
	if (!hasAntecedent(curr_lit)) {
		minimizeAndStoreUIPClause(curr_lit.neg(), tmp_clause, seen);
	}
//	if (var(curr_lit).decision_level > assertion_level_)
//		assertion_level_ = var(curr_lit).decision_level;
}
Example #6
0
/** execution method of primal heuristic */
static
SCIP_DECL_HEUREXEC(heurExecRounding) /*lint --e{715}*/
{  /*lint --e{715}*/
   SCIP_HEURDATA* heurdata;
   SCIP_SOL* sol;
   SCIP_VAR** lpcands;
   SCIP_Real* lpcandssol;
   SCIP_ROW** lprows;
   SCIP_Real* activities;
   SCIP_ROW** violrows;
   int* violrowpos;
   SCIP_Real obj;
   SCIP_Real bestroundval;
   SCIP_Real minobj;
   int nlpcands;
   int nlprows;
   int nfrac;
   int nviolrows;
   int c;
   int r;
   SCIP_Longint nlps;
   SCIP_Longint ncalls;
   SCIP_Longint nsolsfound;
   SCIP_Longint nnodes;

   assert(strcmp(SCIPheurGetName(heur), HEUR_NAME) == 0);
   assert(scip != NULL);
   assert(result != NULL);
   assert(SCIPhasCurrentNodeLP(scip));

   *result = SCIP_DIDNOTRUN;

   /* only call heuristic, if an optimal LP solution is at hand */
   if( SCIPgetLPSolstat(scip) != SCIP_LPSOLSTAT_OPTIMAL )
      return SCIP_OKAY;

   /* only call heuristic, if the LP objective value is smaller than the cutoff bound */
   if( SCIPisGE(scip, SCIPgetLPObjval(scip), SCIPgetCutoffbound(scip)) )
      return SCIP_OKAY;

   /* get heuristic data */
   heurdata = SCIPheurGetData(heur);
   assert(heurdata != NULL);

   /* don't call heuristic, if we have already processed the current LP solution */
   nlps = SCIPgetNLPs(scip);
   if( nlps == heurdata->lastlp )
      return SCIP_OKAY;
   heurdata->lastlp = nlps;

   /* don't call heuristic, if it was not successful enough in the past */
   ncalls = SCIPheurGetNCalls(heur);
   nsolsfound = 10*SCIPheurGetNBestSolsFound(heur) + SCIPheurGetNSolsFound(heur);
   nnodes = SCIPgetNNodes(scip);
   if( nnodes % ((ncalls/heurdata->successfactor)/(nsolsfound+1)+1) != 0 )
      return SCIP_OKAY;

   /* get fractional variables, that should be integral */
   SCIP_CALL( SCIPgetLPBranchCands(scip, &lpcands, &lpcandssol, NULL, &nlpcands, NULL, NULL) );
   nfrac = nlpcands;

   /* only call heuristic, if LP solution is fractional */
   if( nfrac == 0 )
      return SCIP_OKAY;

   *result = SCIP_DIDNOTFIND;

   /* get LP rows */
   SCIP_CALL( SCIPgetLPRowsData(scip, &lprows, &nlprows) );

   SCIPdebugMessage("executing rounding heuristic: %d LP rows, %d fractionals\n", nlprows, nfrac);

   /* get memory for activities, violated rows, and row violation positions */
   SCIP_CALL( SCIPallocBufferArray(scip, &activities, nlprows) );
   SCIP_CALL( SCIPallocBufferArray(scip, &violrows, nlprows) );
   SCIP_CALL( SCIPallocBufferArray(scip, &violrowpos, nlprows) );

   /* get the activities for all globally valid rows;
    * the rows should be feasible, but due to numerical inaccuracies in the LP solver, they can be violated
    */
   nviolrows = 0;
   for( r = 0; r < nlprows; ++r )
   {
      SCIP_ROW* row;

      row = lprows[r];
      assert(SCIProwGetLPPos(row) == r);

      if( !SCIProwIsLocal(row) )
      {
         activities[r] = SCIPgetRowActivity(scip, row);
         if( SCIPisFeasLT(scip, activities[r], SCIProwGetLhs(row))
            || SCIPisFeasGT(scip, activities[r], SCIProwGetRhs(row)) )
         {
            violrows[nviolrows] = row;
            violrowpos[r] = nviolrows;
            nviolrows++;
         }
         else
            violrowpos[r] = -1;
      }
   }

   /* get the working solution from heuristic's local data */
   sol = heurdata->sol;
   assert(sol != NULL);

   /* copy the current LP solution to the working solution */
   SCIP_CALL( SCIPlinkLPSol(scip, sol) );

   /* calculate the minimal objective value possible after rounding fractional variables */
   minobj = SCIPgetSolTransObj(scip, sol);
   assert(minobj < SCIPgetCutoffbound(scip));
   for( c = 0; c < nlpcands; ++c )
   {
      obj = SCIPvarGetObj(lpcands[c]);
      bestroundval = obj > 0.0 ? SCIPfeasFloor(scip, lpcandssol[c]) : SCIPfeasCeil(scip, lpcandssol[c]);
      minobj += obj * (bestroundval - lpcandssol[c]);
   }

   /* try to round remaining variables in order to become/stay feasible */
   while( nfrac > 0 )
   {
      SCIP_VAR* roundvar;
      SCIP_Real oldsolval;
      SCIP_Real newsolval;

      SCIPdebugMessage("rounding heuristic: nfrac=%d, nviolrows=%d, obj=%g (best possible obj: %g)\n",
         nfrac, nviolrows, SCIPgetSolOrigObj(scip, sol), SCIPretransformObj(scip, minobj));

      /* minobj < SCIPgetCutoffbound(scip) should be true, otherwise the rounding variable selection
       * should have returned NULL. Due to possible cancellation we use SCIPisLE. */
      assert( SCIPisLE(scip, minobj, SCIPgetCutoffbound(scip)) );

      /* choose next variable to process:
       *  - if a violated row exists, round a variable decreasing the violation, that has least impact on other rows
       *  - otherwise, round a variable, that has strongest devastating impact on rows in opposite direction
       */
      if( nviolrows > 0 )
      {
         SCIP_ROW* row;
         int rowpos;

         row = violrows[nviolrows-1];
         rowpos = SCIProwGetLPPos(row);
         assert(0 <= rowpos && rowpos < nlprows);
         assert(violrowpos[rowpos] == nviolrows-1);

         SCIPdebugMessage("rounding heuristic: try to fix violated row <%s>: %g <= %g <= %g\n",
            SCIProwGetName(row), SCIProwGetLhs(row), activities[rowpos], SCIProwGetRhs(row));
         if( SCIPisFeasLT(scip, activities[rowpos], SCIProwGetLhs(row)) )
         {
            /* lhs is violated: select a variable rounding, that increases the activity */
            SCIP_CALL( selectIncreaseRounding(scip, sol, minobj, row, &roundvar, &oldsolval, &newsolval) );
         }
         else
         {
            assert(SCIPisFeasGT(scip, activities[rowpos], SCIProwGetRhs(row)));
            /* rhs is violated: select a variable rounding, that decreases the activity */
            SCIP_CALL( selectDecreaseRounding(scip, sol, minobj, row, &roundvar, &oldsolval, &newsolval) );
         }
      }
      else
      {
         SCIPdebugMessage("rounding heuristic: search rounding variable and try to stay feasible\n");
         SCIP_CALL( selectEssentialRounding(scip, sol, minobj, lpcands, nlpcands, &roundvar, &oldsolval, &newsolval) );
      }

      /* check, whether rounding was possible */
      if( roundvar == NULL )
      {
         SCIPdebugMessage("rounding heuristic:  -> didn't find a rounding variable\n");
         break;
      }

      SCIPdebugMessage("rounding heuristic:  -> round var <%s>, oldval=%g, newval=%g, obj=%g\n",
         SCIPvarGetName(roundvar), oldsolval, newsolval, SCIPvarGetObj(roundvar));

      /* update row activities of globally valid rows */
      SCIP_CALL( updateActivities(scip, activities, violrows, violrowpos, &nviolrows, nlprows, 
            roundvar, oldsolval, newsolval) );

      /* store new solution value and decrease fractionality counter */
      SCIP_CALL( SCIPsetSolVal(scip, sol, roundvar, newsolval) );
      nfrac--;

      /* update minimal objective value possible after rounding remaining variables */
      obj = SCIPvarGetObj(roundvar);
      if( obj > 0.0 && newsolval > oldsolval )
         minobj += obj;
      else if( obj < 0.0 && newsolval < oldsolval )
         minobj -= obj;

      SCIPdebugMessage("rounding heuristic:  -> nfrac=%d, nviolrows=%d, obj=%g (best possible obj: %g)\n",
         nfrac, nviolrows, SCIPgetSolOrigObj(scip, sol), SCIPretransformObj(scip, minobj));
   }

   /* check, if the new solution is feasible */
   if( nfrac == 0 && nviolrows == 0 )
   {
      SCIP_Bool stored;

      /* check solution for feasibility, and add it to solution store if possible
       * neither integrality nor feasibility of LP rows has to be checked, because this is already
       * done in the rounding heuristic itself; however, be better check feasibility of LP rows,
       * because of numerical problems with activity updating
       */
      SCIP_CALL( SCIPtrySol(scip, sol, FALSE, FALSE, FALSE, TRUE, &stored) );

      if( stored )
      {
#ifdef SCIP_DEBUG
         SCIPdebugMessage("found feasible rounded solution:\n");
         SCIP_CALL( SCIPprintSol(scip, sol, NULL, FALSE) );
#endif
         *result = SCIP_FOUNDSOL;
      }
   }

   /* free memory buffers */
   SCIPfreeBufferArray(scip, &violrowpos);
   SCIPfreeBufferArray(scip, &violrows);
   SCIPfreeBufferArray(scip, &activities);

   return SCIP_OKAY;
}