/// <summary>
/// Calculates the number of sub-steps for each sub-grid
/// </summary>
protected Clusterer.Clustering CalculateNumberOfLocalTS(Clusterer.Clustering clustering)
{
NumberOfLocalTimeSteps.Clear();
double[] sendHmin = new double[clustering.NumberOfClusters];
double[] rcvHmin = new double[clustering.NumberOfClusters];
MultidimensionalArray cellMetric = clusterer.GetStableTimestepSize(clustering.SubGrid);
for (int i = 0; i < clustering.NumberOfClusters; i++)
{
double h_min = double.MaxValue;
CellMask volumeMask = clustering.Clusters[i].VolumeMask;
foreach (Chunk c in volumeMask)
{
int JE = c.JE;
for (int j = c.i0; j < JE; j++)
{
h_min = Math.Min(cellMetric[clustering.SubGrid.LocalCellIndex2SubgridIndex[j]], h_min);
}
}
sendHmin[i] = h_min;
}
// MPI to ensure that each processor has the local time step sizes
unsafe
{
fixed(double *pSend = sendHmin, pRcv = rcvHmin)
{
csMPI.Raw.Allreduce((IntPtr)(pSend), (IntPtr)(pRcv), clustering.NumberOfClusters, csMPI.Raw._DATATYPE.DOUBLE, csMPI.Raw._OP.MIN, csMPI.Raw._COMM.WORLD);
}
}
int[] numOfSubSteps = new int[clustering.NumberOfClusters];
for (int i = 0; i < numOfSubSteps.Length; i++)
{
double fraction = rcvHmin[0] / rcvHmin[i];
// Accounting for roundoff errors
double eps = 1.0e-2;
int subSteps;
if (fraction > Math.Floor(fraction) + eps)
{
subSteps = (int)Math.Ceiling(fraction);
}
else
{
subSteps = (int)Math.Floor(fraction);
}
numOfSubSteps[i] = subSteps;
}
List <SubGrid> newClusters = new List <SubGrid>();
for (int i = 0; i < clustering.NumberOfClusters; i++)
{
if (i < clustering.NumberOfClusters - 1 && numOfSubSteps[i] == numOfSubSteps[i + 1])
{
// Combine both sub-grids and remove the previous one
SubGrid combinedSubGrid = new SubGrid(clustering.Clusters[i].VolumeMask.Union(clustering.Clusters[i + 1].VolumeMask));
newClusters.Add(combinedSubGrid);
Debug.WriteLine("CalculateNumberOfLocalTS: Clustering leads to sub-grids which are too similar, i.e. they have the same number of local time steps. They are combined.");
NumberOfLocalTimeSteps.Add(numOfSubSteps[i]);
i++;
}
else
{
newClusters.Add(clustering.Clusters[i]);
NumberOfLocalTimeSteps.Add(numOfSubSteps[i]);
}
}
#if DEBUG
Console.WriteLine("COMBINING CLUSTERS");
for (int i = 0; i < newClusters.Count; i++)
{
Console.WriteLine("id=" + i + " -> sub-steps=" + NumberOfLocalTimeSteps[i] + " and elements=" + newClusters[i].GlobalNoOfCells);
}
#endif
return(new Clusterer.Clustering(newClusters, clustering.SubGrid));
}