// change the current r value
public void UpdateR(double oldr, double newr, double h)
{
Point v = _profile.First((Point v2) => (v2.X == oldr && v2.Y == h));
if (v.X == oldr)
{
_profile.Remove(v);
_profile.Add(new Point(newr, h));
}
if (_profile.Count > 1)
{
_profile.Sort <Point>((Point pt) => pt, _xascending);
}
}