This function finds the distance between two points.

Parameters:

• 1: double x1 - x coordinate of first point.
• 2: double y1 - y coordinate of first point.
• 3: double z1 - z coordinate of first point.
• 4: double x2 - x coordinate of second point.
• 5: double y2 - y coordinate of second point.
• 6: double z2 - z coordinate of second point.

Responds:

• X where X is the distance between the two points

Reports:

• done when the task completes.

Example:

• User sends: "fd 512 0 0 0 3 4 12"
• Director replies: "rs fd 512 13.000001"
• Director replies: "cp fd 512 done"