changes made:

1. added <> steps
2. added trail of object of visualizing, courtesy of Prof hwang's code
3. added the coordinates ( T[jid,yv[jid] ) to be shown when mouse over for clarity of exploring data points
4. made the checkboxes remember previous selection for ease of inquiry learning
5. added more boolean checkboxes for visualization of quantities
now and before a recent scanning of good applets :)

source codes in zip in attached here cos i can't attach at the top post without messing up the picture preview