/** checks if a given branching candidate is better than a previous one and updates the best branching candidate accordingly */
static
SCIP_RETCODE updateBestCandidate(
SCIP* scip, /**< SCIP data structure */
SCIP_BRANCHRULEDATA* branchruledata, /**< branching rule data */
SCIP_VAR** bestvar, /**< best branching candidate */
SCIP_Real* bestbrpoint, /**< branching point for best branching candidate */
SCIP_Real* bestscore, /**< score of best branching candidate */
SCIP_VAR* cand, /**< branching candidate to consider */
SCIP_Real candscoremin, /**< minimal score of branching candidate */
SCIP_Real candscoremax, /**< maximal score of branching candidate */
SCIP_Real candscoresum, /**< sum of scores of branching candidate */
SCIP_Real candsol /**< proposed branching point of branching candidate */
)
{
SCIP_Real candbrpoint;
SCIP_Real branchscore;
SCIP_Real deltaminus;
SCIP_Real deltaplus;
SCIP_Real pscostdown;
SCIP_Real pscostup;
char strategy;
assert(scip != NULL);
assert(branchruledata != NULL);
assert(bestvar != NULL);
assert(bestbrpoint != NULL);
assert(bestscore != NULL);
assert(cand != NULL);
/* a branching variable candidate should either be an active problem variable or a multi-aggregated variable */
assert(SCIPvarIsActive(SCIPvarGetProbvar(cand)) ||
SCIPvarGetStatus(SCIPvarGetProbvar(cand)) == SCIP_VARSTATUS_MULTAGGR);
if( SCIPvarGetStatus(SCIPvarGetProbvar(cand)) == SCIP_VARSTATUS_MULTAGGR )
{
/* for a multi-aggregated variable, we call updateBestCandidate function recursively with all variables in the multi-aggregation */
SCIP_VAR** multvars;
int nmultvars;
int i;
SCIP_Bool success;
SCIP_Real multvarlb;
SCIP_Real multvarub;
cand = SCIPvarGetProbvar(cand);
multvars = SCIPvarGetMultaggrVars(cand);
nmultvars = SCIPvarGetMultaggrNVars(cand);
/* if we have a candidate branching point, then first register only aggregation variables
* for which we can compute a corresponding branching point too (see also comments below)
* if this fails, then register all (unfixed) aggregation variables, thereby forgetting about candsol
*/
success = FALSE;
if( candsol != SCIP_INVALID ) /*lint !e777*/
{
SCIP_Real* multscalars;
SCIP_Real minact;
SCIP_Real maxact;
SCIP_Real aggrvarsol;
SCIP_Real aggrvarsol1;
SCIP_Real aggrvarsol2;
multscalars = SCIPvarGetMultaggrScalars(cand);
/* for computing the branching point, we need the current bounds of the multi-aggregated variable */
minact = SCIPcomputeVarLbLocal(scip, cand);
maxact = SCIPcomputeVarUbLocal(scip, cand);
for( i = 0; i < nmultvars; ++i )
{
/* skip fixed variables */
multvarlb = SCIPcomputeVarLbLocal(scip, multvars[i]);
multvarub = SCIPcomputeVarUbLocal(scip, multvars[i]);
if( SCIPisEQ(scip, multvarlb, multvarub) )
continue;
assert(multscalars != NULL);
assert(multscalars[i] != 0.0);
/* we cannot ensure that both the upper bound in the left node and the lower bound in the right node
* will be candsol by a clever choice for the branching point of multvars[i],
* but we can try to ensure that at least one of them will be at candsol
*/
if( multscalars[i] > 0.0 )
{
/* cand >= candsol
* if multvars[i] >= (candsol - (maxact - multscalars[i] * ub(multvars[i]))) / multscalars[i]
* = (candsol - maxact) / multscalars[i] + ub(multvars[i])
*/
aggrvarsol1 = (candsol - maxact) / multscalars[i] + multvarub;
/* cand <= candsol
* if multvars[i] <= (candsol - (minact - multscalar[i] * lb(multvars[i]))) / multscalars[i]
* = (candsol - minact) / multscalars[i] + lb(multvars[i])
*/
aggrvarsol2 = (candsol - minact) / multscalars[i] + multvarlb;
}
else
{
/* cand >= candsol
* if multvars[i] <= (candsol - (maxact - multscalars[i] * lb(multvars[i]))) / multscalars[i]
* = (candsol - maxact) / multscalars[i] + lb(multvars[i])
*/
aggrvarsol2 = (candsol - maxact) / multscalars[i] + multvarlb;
/* cand <= candsol
* if multvars[i] >= (candsol - (minact - multscalar[i] * ub(multvars[i]))) / multscalars[i]
* = (candsol - minact) / multscalars[i] + ub(multvars[i])
*/
aggrvarsol1 = (candsol - minact) / multscalars[i] + multvarub;
}
/* by the above choice, aggrvarsol1 <= ub(multvars[i]) and aggrvarsol2 >= lb(multvars[i])
* if aggrvarsol1 <= lb(multvars[i]) or aggrvarsol2 >= ub(multvars[i]), then choose the other one
* if both are out of bounds, then give up
* if both are inside bounds, then choose the one closer to 0.0 (someone has better idea???)
*/
if( SCIPisFeasLE(scip, aggrvarsol1, multvarlb) )
{
if( SCIPisFeasGE(scip, aggrvarsol2, multvarub) )
continue;
else
aggrvarsol = aggrvarsol2;
}
else
{
if( SCIPisFeasGE(scip, aggrvarsol2, multvarub) )
aggrvarsol = aggrvarsol1;
else
aggrvarsol = REALABS(aggrvarsol1) < REALABS(aggrvarsol2) ? aggrvarsol1 : aggrvarsol2;
}
success = TRUE;
SCIP_CALL( updateBestCandidate(scip, branchruledata, bestvar, bestbrpoint, bestscore,
multvars[i], candscoremin, candscoremax, candscoresum, aggrvarsol) );
}
}
if( !success )
for( i = 0; i < nmultvars; ++i )
{
/* skip fixed variables */
multvarlb = SCIPcomputeVarLbLocal(scip, multvars[i]);
multvarub = SCIPcomputeVarUbLocal(scip, multvars[i]);
if( SCIPisEQ(scip, multvarlb, multvarub) )
continue;
SCIP_CALL( updateBestCandidate(scip, branchruledata, bestvar, bestbrpoint, bestscore,
multvars[i], candscoremin, candscoremax, candscoresum, SCIP_INVALID) );
}
assert(*bestvar != NULL); /* if all variables were fixed, something is strange */
return SCIP_OKAY;
}
/* select branching point for this variable */
candbrpoint = SCIPgetBranchingPoint(scip, cand, candsol);
assert(candbrpoint >= SCIPvarGetLbLocal(cand));
assert(candbrpoint <= SCIPvarGetUbLocal(cand));
/* we cannot branch on a huge value for a discrete variable, because we simply cannot enumerate such huge integer values in floating point
* arithmetics
*/
if( SCIPvarGetType(cand) != SCIP_VARTYPE_CONTINUOUS && (SCIPisHugeValue(scip, candbrpoint) || SCIPisHugeValue(scip, -candbrpoint)) )
return SCIP_OKAY;
assert(SCIPvarGetType(cand) == SCIP_VARTYPE_CONTINUOUS || !SCIPisIntegral(scip, candbrpoint));
if( SCIPvarGetType(cand) == SCIP_VARTYPE_CONTINUOUS )
strategy = (branchruledata->strategy == 'u' ? branchruledata->updatestrategy : branchruledata->strategy);
else
strategy = (branchruledata->strategy == 'u' ? 'l' : branchruledata->strategy);
switch( strategy )
{
case 'l':
if( SCIPisInfinity(scip, SCIPgetSolVal(scip, NULL, cand)) || SCIPgetSolVal(scip, NULL, cand) <= SCIPadjustedVarUb(scip, cand, candbrpoint) )
deltaminus = 0.0;
else
deltaminus = SCIPgetSolVal(scip, NULL, cand) - SCIPadjustedVarUb(scip, cand, candbrpoint);
if( SCIPisInfinity(scip, -SCIPgetSolVal(scip, NULL, cand)) || SCIPgetSolVal(scip, NULL, cand) >= SCIPadjustedVarLb(scip, cand, candbrpoint) )
deltaplus = 0.0;
else
deltaplus = SCIPadjustedVarLb(scip, cand, candbrpoint) - SCIPgetSolVal(scip, NULL, cand);
break;
case 'd':
if( SCIPisInfinity(scip, -SCIPvarGetLbLocal(cand)) )
deltaminus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
else
deltaminus = SCIPadjustedVarUb(scip, cand, candbrpoint) - SCIPvarGetLbLocal(cand);
if( SCIPisInfinity(scip, SCIPvarGetUbLocal(cand)) )
deltaplus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
else
deltaplus = SCIPvarGetUbLocal(cand) - SCIPadjustedVarLb(scip, cand, candbrpoint);
break;
case 's':
if( SCIPisInfinity(scip, -SCIPvarGetLbLocal(cand)) )
deltaplus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
else
deltaplus = SCIPadjustedVarUb(scip, cand, candbrpoint) - SCIPvarGetLbLocal(cand);
if( SCIPisInfinity(scip, SCIPvarGetUbLocal(cand)) )
deltaminus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
else
deltaminus = SCIPvarGetUbLocal(cand) - SCIPadjustedVarLb(scip, cand, candbrpoint);
break;
case 'v':
deltaplus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
deltaminus = deltaplus;
break;
default :
SCIPerrorMessage("branching strategy %c unknown\n", strategy);
SCIPABORT();
return SCIP_INVALIDDATA; /*lint !e527*/
}
if( SCIPisInfinity(scip, deltaminus) || SCIPisInfinity(scip, deltaplus) )
{
branchscore = SCIPinfinity(scip);
}
else
{
pscostdown = SCIPgetVarPseudocostVal(scip, cand, -deltaminus);
pscostup = SCIPgetVarPseudocostVal(scip, cand, deltaplus);
branchscore = SCIPgetBranchScore(scip, cand, pscostdown, pscostup);
assert(!SCIPisNegative(scip, branchscore));
}
SCIPdebugMessage("branching score variable <%s>[%g,%g] = %g; wscore = %g; type=%d bestbrscore=%g\n",
SCIPvarGetName(cand), SCIPvarGetLbLocal(cand), SCIPvarGetUbLocal(cand), branchscore, WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum),
SCIPvarGetType(cand), *bestscore);
if( SCIPisInfinity(scip, branchscore) )
branchscore = 0.9*SCIPinfinity(scip);
if( SCIPisSumGT(scip, branchscore, *bestscore) )
{
(*bestscore) = branchscore;
(*bestvar) = cand;
(*bestbrpoint) = candbrpoint;
}
else if( SCIPisSumEQ(scip, branchscore, *bestscore)
&& !(SCIPisInfinity(scip, -SCIPvarGetLbLocal(*bestvar)) && SCIPisInfinity(scip, SCIPvarGetUbLocal(*bestvar))) )
{
/* if best candidate so far is not unbounded to both sides, maybe take new candidate */
if( (SCIPisInfinity(scip, -SCIPvarGetLbLocal(cand)) || SCIPisInfinity(scip, SCIPvarGetUbLocal(cand))) &&
(SCIPisInfinity(scip, -SCIPvarGetLbLocal(*bestvar)) || SCIPisInfinity(scip, SCIPvarGetUbLocal(*bestvar))) )
{
/* if both variables are unbounded but one of them is bounded on one side, take the one with the larger bound on this side (hope that this avoids branching on always the same variable) */
if( SCIPvarGetUbLocal(cand) > SCIPvarGetUbLocal(*bestvar) || SCIPvarGetLbLocal(cand) < SCIPvarGetLbLocal(*bestvar) )
{
(*bestscore) = branchscore;
(*bestvar) = cand;
(*bestbrpoint) = candbrpoint;
}
}
else if( SCIPvarGetType(*bestvar) == SCIPvarGetType(cand) )
{
/* if both have the same type, take the one with larger diameter */
if( SCIPvarGetUbLocal(*bestvar) - SCIPvarGetLbLocal(*bestvar) < SCIPvarGetUbLocal(cand) - SCIPvarGetLbLocal(cand) )
{
(*bestscore) = branchscore;
(*bestvar) = cand;
(*bestbrpoint) = candbrpoint;
}
}
else if( SCIPvarGetType(*bestvar) > SCIPvarGetType(cand) )
{
/* take the one with better type ("more discrete") */
(*bestscore) = branchscore;
(*bestvar) = cand;
(*bestbrpoint) = candbrpoint;
}
}
return SCIP_OKAY;
}
/** evalutate solution */
SCIP_RETCODE LOPevalSolution(
SCIP* scip /**< SCIP data structure */
)
{
SCIP_PROBDATA* probdata;
SCIP_VAR*** vars;
SCIP_SOL* sol;
int* outDegree;
int* indices;
int i;
int j;
int n;
/* get problem data */
probdata = SCIPgetProbData(scip);
assert( probdata != NULL );
assert( probdata->vars != NULL );
n = probdata->n;
vars = probdata->vars;
sol = SCIPgetBestSol(scip);
if ( sol == NULL )
printf("\nNo solution found.\n");
else
{
SCIP_CALL( SCIPallocBufferArray(scip, &outDegree, n) );
SCIP_CALL( SCIPallocBufferArray(scip, &indices, n) );
/* compute out-degree */
for (i = 0; i < n; ++i)
{
int deg = 0;
for (j = 0; j < n; ++j)
{
SCIP_Real val;
if (j == i)
continue;
val = SCIPgetSolVal(scip, sol, vars[i][j]);
assert( SCIPisIntegral(scip, val) );
if ( val < 0.5 )
++deg;
}
outDegree[i] = deg;
indices[i] = i;
}
/* sort such that degrees are non-decreasing */
SCIPsortIntInt(outDegree, indices, n);
/* output */
printf("\nFinal order:\n");
for (i = 0; i < n; ++i)
printf("%d ", indices[i]);
printf("\n");
SCIPfreeBufferArray(scip, &indices);
SCIPfreeBufferArray(scip, &outDegree);
}
return SCIP_OKAY;
}
/** presolving execution method */
static
SCIP_DECL_PRESOLEXEC(presolExecBoundshift)
{ /*lint --e{715}*/
SCIP_PRESOLDATA* presoldata;
SCIP_VAR** scipvars;
SCIP_VAR** vars;
int nbinvars;
int nvars;
int v;
assert(scip != NULL);
assert(presol != NULL);
assert(strcmp(SCIPpresolGetName(presol), PRESOL_NAME) == 0);
assert(result != NULL);
*result = SCIP_DIDNOTRUN;
/* get presolver data */
presoldata = SCIPpresolGetData(presol);
assert(presoldata != NULL);
/* get the problem variables */
scipvars = SCIPgetVars(scip);
nbinvars = SCIPgetNBinVars(scip);
nvars = SCIPgetNVars(scip) - nbinvars;
if( nvars == 0 )
return SCIP_OKAY;
if( SCIPdoNotAggr(scip) )
return SCIP_OKAY;
*result = SCIP_DIDNOTFIND;
/* copy the integer variables into an own array, since adding new integer variables affects the left-most slots in
* the array and thereby interferes with our search loop
*/
SCIP_CALL( SCIPduplicateBufferArray(scip, &vars, &scipvars[nbinvars], nvars) );
/* scan the integer, implicit, and continuous variables for possible conversion */
for( v = nvars - 1; v >= 0; --v )
{
SCIP_VAR* var = vars[v];
SCIP_Real lb;
SCIP_Real ub;
assert(SCIPvarGetType(var) != SCIP_VARTYPE_BINARY);
/* get current variable's bounds */
lb = SCIPvarGetLbGlobal(var);
ub = SCIPvarGetUbGlobal(var);
assert( SCIPisLE(scip, lb, ub) );
if( SCIPisEQ(scip, lb, ub) )
continue;
if( presoldata->integer && !SCIPisIntegral(scip, ub - lb) )
continue;
/* check if bounds are shiftable */
if( !SCIPisEQ(scip, lb, 0.0) && /* lower bound != 0.0 */
SCIPisLT(scip, ub, SCIPinfinity(scip)) && /* upper bound != infinity */
SCIPisGT(scip, lb, -SCIPinfinity(scip)) && /* lower bound != -infinity */
#if 0
SCIPisLT(scip, ub - lb, SCIPinfinity(scip)) && /* interval length less than SCIPinfinity(scip) */
#endif
SCIPisLT(scip, ub - lb, (SCIP_Real) presoldata->maxshift) ) /* less than max shifting */
{
SCIP_VAR* newvar;
char newvarname[SCIP_MAXSTRLEN];
SCIP_Bool infeasible;
SCIP_Bool redundant;
SCIP_Bool aggregated;
SCIPdebugMessage("convert range <%s>[%g,%g] to [%g,%g]\n", SCIPvarGetName(var), lb, ub, 0.0, (ub - lb) );
/* create new variable */
(void) SCIPsnprintf(newvarname, SCIP_MAXSTRLEN, "%s_shift", SCIPvarGetName(var));
SCIP_CALL( SCIPcreateVar(scip, &newvar, newvarname, 0.0, (ub - lb), 0.0, SCIPvarGetType(var),
SCIPvarIsInitial(var), SCIPvarIsRemovable(var), NULL, NULL, NULL, NULL, NULL) );
SCIP_CALL( SCIPaddVar(scip, newvar) );
/* aggregate old variable with new variable */
if( presoldata->flipping )
{
if( REALABS(ub) < REALABS(lb) )
{
SCIP_CALL( SCIPaggregateVars(scip, var, newvar, 1.0, 1.0, ub, &infeasible, &redundant, &aggregated) );
}
else
{
SCIP_CALL( SCIPaggregateVars(scip, var, newvar, 1.0, -1.0, lb, &infeasible, &redundant, &aggregated) );
}
}
else
{
SCIP_CALL( SCIPaggregateVars(scip, var, newvar, 1.0, -1.0, lb, &infeasible, &redundant, &aggregated) );
}
assert(!infeasible);
assert(redundant);
assert(aggregated);
SCIPdebugMessage("var <%s> with bounds [%f,%f] has obj %f\n",
SCIPvarGetName(newvar),SCIPvarGetLbGlobal(newvar),SCIPvarGetUbGlobal(newvar),SCIPvarGetObj(newvar));
/* release variable */
SCIP_CALL( SCIPreleaseVar(scip, &newvar) );
/* take care of statistic */
(*naggrvars)++;
*result = SCIP_SUCCESS;
}
}
/* free temporary memory */
SCIPfreeBufferArray(scip, &vars);
return SCIP_OKAY;
}
/** calculate the branching score of a variable, depending on the chosen score parameter */
static
SCIP_RETCODE calcBranchScore(
SCIP* scip, /**< current SCIP */
SCIP_HEURDATA* heurdata, /**< branch rule data */
SCIP_VAR* var, /**< candidate variable */
SCIP_Real lpsolval, /**< current fractional LP-relaxation solution value */
SCIP_Real* upscore, /**< pointer to store the variable score when branching on it in upward direction */
SCIP_Real* downscore, /**< pointer to store the variable score when branching on it in downward direction */
char scoreparam /**< the score parameter of this heuristic */
)
{
SCIP_COL* varcol;
SCIP_ROW** colrows;
SCIP_Real* rowvals;
SCIP_Real varlb;
SCIP_Real varub;
SCIP_Real squaredbounddiff; /* current squared difference of variable bounds (ub - lb)^2 */
SCIP_Real newub; /* new upper bound if branching downwards */
SCIP_Real newlb; /* new lower bound if branching upwards */
SCIP_Real squaredbounddiffup; /* squared difference after branching upwards (ub - lb')^2 */
SCIP_Real squaredbounddiffdown; /* squared difference after branching downwards (ub' - lb)^2 */
SCIP_Real currentmean; /* current mean value of variable uniform distribution */
SCIP_Real meanup; /* mean value of variable uniform distribution after branching up */
SCIP_Real meandown; /* mean value of variable uniform distribution after branching down*/
SCIP_VARTYPE vartype;
int ncolrows;
int i;
SCIP_Bool onlyactiverows; /* should only rows which are active at the current node be considered? */
assert(scip != NULL);
assert(var != NULL);
assert(upscore != NULL);
assert(downscore != NULL);
assert(!SCIPisIntegral(scip, lpsolval) || SCIPvarIsBinary(var));
assert(SCIPvarGetStatus(var) == SCIP_VARSTATUS_COLUMN);
varcol = SCIPvarGetCol(var);
assert(varcol != NULL);
colrows = SCIPcolGetRows(varcol);
rowvals = SCIPcolGetVals(varcol);
ncolrows = SCIPcolGetNNonz(varcol);
varlb = SCIPvarGetLbLocal(var);
varub = SCIPvarGetUbLocal(var);
assert(SCIPisFeasLT(scip, varlb, varub));
vartype = SCIPvarGetType(var);
/* calculate mean and variance of variable uniform distribution before and after branching */
currentmean = 0.0;
squaredbounddiff = 0.0;
SCIPvarCalcDistributionParameters(scip, varlb, varub, vartype, ¤tmean, &squaredbounddiff);
/* unfixed binary variables may have an integer solution value in the LP solution, eg, at the presence of indicator constraints */
if( !SCIPvarIsBinary(var) )
{
newlb = SCIPfeasCeil(scip, lpsolval);
newub = SCIPfeasFloor(scip, lpsolval);
}
else
{
newlb = 1.0;
newub = 0.0;
}
/* calculate the variable's uniform distribution after branching up and down, respectively. */
squaredbounddiffup = 0.0;
meanup = 0.0;
SCIPvarCalcDistributionParameters(scip, newlb, varub, vartype, &meanup, &squaredbounddiffup);
/* calculate the distribution mean and variance for a variable with finite lower bound */
squaredbounddiffdown = 0.0;
meandown = 0.0;
SCIPvarCalcDistributionParameters(scip, varlb, newub, vartype, &meandown, &squaredbounddiffdown);
/* initialize the variable's up and down score */
*upscore = 0.0;
*downscore = 0.0;
onlyactiverows = FALSE;
/* loop over the variable rows and calculate the up and down score */
for( i = 0; i < ncolrows; ++i )
{
SCIP_ROW* row;
SCIP_Real changedrowmean;
SCIP_Real rowmean;
SCIP_Real rowvariance;
SCIP_Real changedrowvariance;
SCIP_Real currentrowprob;
SCIP_Real newrowprobup;
SCIP_Real newrowprobdown;
SCIP_Real squaredcoeff;
SCIP_Real rowval;
int rowinfinitiesdown;
int rowinfinitiesup;
int rowpos;
row = colrows[i];
rowval = rowvals[i];
assert(row != NULL);
/* we access the rows by their index */
rowpos = SCIProwGetIndex(row);
/* skip non-active rows if the user parameter was set this way */
if( onlyactiverows && SCIPisSumPositive(scip, SCIPgetRowLPFeasibility(scip, row)) )
continue;
/* call method to ensure sufficient data capacity */
SCIP_CALL( heurdataEnsureArraySize(scip, heurdata, rowpos) );
/* calculate row activity distribution if this is the first candidate to appear in this row */
if( heurdata->rowmeans[rowpos] == SCIP_INVALID ) /*lint !e777 doesn't like comparing floats for equality */
{
rowCalculateGauss(scip, heurdata, row, &heurdata->rowmeans[rowpos], &heurdata->rowvariances[rowpos],
&heurdata->rowinfinitiesdown[rowpos], &heurdata->rowinfinitiesup[rowpos]);
}
/* retrieve the row distribution parameters from the branch rule data */
rowmean = heurdata->rowmeans[rowpos];
rowvariance = heurdata->rowvariances[rowpos];
rowinfinitiesdown = heurdata->rowinfinitiesdown[rowpos];
rowinfinitiesup = heurdata->rowinfinitiesup[rowpos];
assert(!SCIPisNegative(scip, rowvariance));
currentrowprob = SCIProwCalcProbability(scip, row, rowmean, rowvariance,
rowinfinitiesdown, rowinfinitiesup);
/* get variable's current expected contribution to row activity */
squaredcoeff = SQUARED(rowval);
/* first, get the probability change for the row if the variable is branched on upwards. The probability
* can only be affected if the variable upper bound is finite
*/
if( !SCIPisInfinity(scip, varub) )
{
int rowinftiesdownafterbranch;
int rowinftiesupafterbranch;
/* calculate how branching would affect the row parameters */
changedrowmean = rowmean + rowval * (meanup - currentmean);
changedrowvariance = rowvariance + squaredcoeff * (squaredbounddiffup - squaredbounddiff);
changedrowvariance = MAX(0.0, changedrowvariance);
rowinftiesdownafterbranch = rowinfinitiesdown;
rowinftiesupafterbranch = rowinfinitiesup;
/* account for changes of the row's infinite bound contributions */
if( SCIPisInfinity(scip, -varlb) && rowval < 0.0 )
rowinftiesupafterbranch--;
if( SCIPisInfinity(scip, -varlb) && rowval > 0.0 )
rowinftiesdownafterbranch--;
assert(rowinftiesupafterbranch >= 0);
assert(rowinftiesdownafterbranch >= 0);
newrowprobup = SCIProwCalcProbability(scip, row, changedrowmean, changedrowvariance, rowinftiesdownafterbranch,
rowinftiesupafterbranch);
}
else
newrowprobup = currentrowprob;
/* do the same for the other branching direction */
if( !SCIPisInfinity(scip, varlb) )
{
int rowinftiesdownafterbranch;
int rowinftiesupafterbranch;
changedrowmean = rowmean + rowval * (meandown - currentmean);
changedrowvariance = rowvariance + squaredcoeff * (squaredbounddiffdown - squaredbounddiff);
changedrowvariance = MAX(0.0, changedrowvariance);
rowinftiesdownafterbranch = rowinfinitiesdown;
rowinftiesupafterbranch = rowinfinitiesup;
/* account for changes of the row's infinite bound contributions */
if( SCIPisInfinity(scip, varub) && rowval > 0.0 )
rowinftiesupafterbranch -= 1;
if( SCIPisInfinity(scip, varub) && rowval < 0.0 )
rowinftiesdownafterbranch -= 1;
assert(rowinftiesdownafterbranch >= 0);
assert(rowinftiesupafterbranch >= 0);
newrowprobdown = SCIProwCalcProbability(scip, row, changedrowmean, changedrowvariance, rowinftiesdownafterbranch,
rowinftiesupafterbranch);
}
else
newrowprobdown = currentrowprob;
/* update the up and down score depending on the chosen scoring parameter */
SCIP_CALL( SCIPupdateDistributionScore(scip, currentrowprob, newrowprobup, newrowprobdown, upscore, downscore, scoreparam) );
SCIPdebugMessage(" Variable %s changes probability of row %s from %g to %g (branch up) or %g;\n",
SCIPvarGetName(var), SCIProwGetName(row), currentrowprob, newrowprobup, newrowprobdown);
SCIPdebugMessage(" --> new variable score: %g (for branching up), %g (for branching down)\n",
*upscore, *downscore);
}
return SCIP_OKAY;
}
