/**
* Return the next edge that will maximize the difference between including it and excluding it.
*/
public Tuple <int, int> getNextEdge()
{
Tuple <int, int> bestEdgeSoFar = null;
double includeBound, excludeBound;
double difference, maxDifference = -1D;
// Loop through all edges
for (int i = 0; i < cm.GetLength(0); i++)
{
for (int j = 0; j < cm.GetLength(1); j++)
{
// If this edge isn't eligible (zero cost), skip it.
if (cm[i, j] != 0)
{
continue;
}
// Ok, this edge is eligible, calculate the inc/exc difference
// For inclusion, make all entries in column i and row j infinite cost.
// then reduce the matrix, adding to the bound as necessary.
// -- If this edge is used, later on in the core algorith we need toremember
// to mark edge [j, i] as infinite as well.
double[,] tempCm = duplicateCM(cm);
tempCm[i, j] = double.PositiveInfinity;
tempCm[j, i] = double.PositiveInfinity;
for (int t = 0; t < tempCm.GetLength(0); t++)
{
tempCm[t, j] = double.PositiveInfinity;
}
for (int t = 0; t < tempCm.GetLength(1); t++)
{
tempCm[i, t] = double.PositiveInfinity;
}
includeBound = bound + ProblemAndSolver.reduceCM(ref tempCm);
// For exclusion, make the cost of [i, j] infinite, then
// b(Se) = b(Sparent) + min(rowi) + min(colj)
tempCm = duplicateCM(cm);
tempCm[i, j] = double.PositiveInfinity;
excludeBound = bound + ProblemAndSolver.reduceCM(ref tempCm);
// Calculate the differnce, check to see if this is lower than the lowest so far
difference = Math.Abs(excludeBound - includeBound);
if (difference > maxDifference)
{
maxDifference = difference;
bestEdgeSoFar = new Tuple <int, int>(i, j);
}
}
}
return(bestEdgeSoFar);
}
