/// <summary>
/// Computes the permutation for the given <paramref name="RowMap"/>
/// </summary>
/// <param name="RowMap"></param>
/// <param name="grd"></param>
/// <returns></returns>
public static int[] ComputePermutation(UnsetteledCoordinateMapping RowMap, GridData grd)
{
int J = grd.Grid.NoOfUpdateCells;
int[] N = RowMap.BasisS.Select(x => x.MaximalLength).ToArray();
int NT = N.Sum();
int Gamma = RowMap.BasisS.Count;
var GlobalIDs = grd.CurrentGlobalIdPermutation.Values;
int[] PermutationTable;
PermutationTable = new int[RowMap.LocalLength];
Debug.Assert(PermutationTable.Length == J * NT);
for (int j = 0; j < J; j++)
{
int gid = (int)GlobalIDs[j];
int iTarg0 = gid * NT;
int i0 = (int)RowMap.LocalUniqueCoordinateIndex(0, j, 0);
for (int f = 0; f < Gamma; f++)
{
for (int n = 0; n < N[f]; n++)
{
int i = (int)RowMap.LocalUniqueCoordinateIndex(f, j, n);
int iTarg = iTarg0 + (i - i0);
PermutationTable[i] = iTarg;
}
}
}
int[] globalPermutationTable = new int[grd.Grid.NumberOfCells * NT];
unsafe {
int[] displ = RowMap.GetI0s().Select(x => (int)x).ToArray();
int[] rcvCnt = new int[RowMap.MpiSize];
for (int i = 0; i < RowMap.MpiSize; i++)
rcvCnt[i] = displ[i + 1] - displ[i];
fixed(int *pSnd = PermutationTable, pRcv = globalPermutationTable, pDispl = displ, pRcvCnt = rcvCnt)
{
csMPI.Raw.Allgatherv((IntPtr)pSnd, PermutationTable.Length, csMPI.Raw._DATATYPE.INT,
(IntPtr)pRcv, (IntPtr)pRcvCnt, (IntPtr)pDispl, csMPI.Raw._DATATYPE.INT,
csMPI.Raw._COMM.WORLD);
}
}
return(globalPermutationTable);
}
