$xd

This function is to determine the position of contact. This function should be use with $contact.

Format

$xd
contact1_start  contact1_end
contact2_start  contact2_end
...
contactn_start  contactn_end

Example

$xd 
-0.0001   19.9999 
25.0000   38.0000 
50.0001   70.0000

$contact 
3    
21 
4   

This function should be use with $contact.

$contact,