This will work out the Virtual Swing Arm Length and Roll Center Height at rest given the 4 suspension pick-up positions and the track.
X being the distance from the Center line of the car.
Y being the distance from the ground.
Tyre Pressure should be check before measuring.
You can put you Co-Ordinates in, in any decimal Unit (metric, imperial) as long as they are all the same units.
If you have parallel top and bottom links you will get a Virtual Swing Arm length on Infinity and a NaN Roll Center Height, as they won't intersect.
Virtual Swing arm is also be known as Instantaneous centre.
Remember Virtual Kingpin Angle is not Camber or Kingpin Angle.