function GCdistanceBetween(a,b) { var rad=0.01745566; Lo=Math.abs(a.lon-b.lon); Drad=Math.acos((Math.sin(a.lat*rad)*Math.sin(b.lat*rad))+(Math.abs(Math.cos(a.lat*rad))*Math.abs(Math.cos(b.lat*rad))*Math.cos(Lo*rad))); Crad=Math.acos((Math.sin(b.lat*rad)-(Math.sin(a.lat*rad)*Math.cos(Drad)))/(Math.cos(a.lat*rad)*Math.sin(Drad))); var Cdeg = Crad * 57.295779; return Drad * 57.295779 * 69.06; }