void UpdateRelativePosition()
{
double[] y = source.Position;
double[] x = target.Position;
double dist = 0;
for (int i = 0; i < 3; i++)
{
double dd = y[i] - x[i];
dist += dd * dd;
relative[i] = dd;
}
distance = Math.Sqrt(dist);
ReferenceFrame f = ReferenceFrame.GetOwnFrame(target);
f.CalculateRotatedPosition(relative, relativePos);
}