/// <summary>
/// A low-Performance method to permute some operator Matrix according to the GlobalID-permutation;
/// </summary>
/// <param name="M"></param>
/// <param name="grd"></param>
/// <param name="RowMap"></param>
/// <param name="ColMap"></param>
/// <returns></returns>
/// <remarks>
/// Low-Performance implementation, only for debugging purposes.
/// </remarks>
public static MsrMatrix ResortMatrix(this MsrMatrix M, GridData grd, UnsetteledCoordinateMapping RowMap, UnsetteledCoordinateMapping ColMap)
{
if (!M.RowPartitioning.Equals(RowMap))
{
throw new ArgumentException();
}
if (!M.ColPartition.Equals(ColMap))
{
throw new ArgumentException();
}
int[] RowPerm = ComputePermutation(RowMap, grd);
int[] ColPerm = ComputePermutation(ColMap, grd);
// permute columns
MsrMatrix M2 = ColumnPermute(M, ColPerm);
// permute rows
MsrMatrix M3 = ColumnPermute(M2.Transpose(), RowPerm).Transpose();
// return
return(M3);
}