lat lon lat lon
12.000 25.125 14.235 25.012
14.200 81.000 25.584 25.014
45.023 25.365 25.152 35.222

 
# calculate distance between two points 
 distance=sqrt((pow(londif*prcurt*cos(meanlat),2))+(pow((latdif*mrcurt),2)));
 latdif=point 1 latitude- point 2 latitude;
 londif=point 1 longitude-point 2 longitude;
 meanlat=(point 1 latitude+point 2 latitude)/2.0;
 a=6377276.345,b=6356075.4131;
 e=sqrt(((a*a)-(b*b))/(a*a));
  function mrcurt(a, e, meanlat)
  {
  mrc=(a*(1-(e*e)))/pow((1-((e*e)*pow(sin(meanlat),2))),1.5);
  return mrc;
  }
  
function prcurt( a, e, meanlat)
  {
 prc;
  prc=a/sqrt(1-pow((e*sin(meanlat)),2));
  return prc;
  }

# calculate Azimuth between two points
A=2*atan((londif/latdif)*((prcurt/mrcurt)*(cos(meanlat))));
  B=londif*(sin(meanlat));
  Az=(A-B)/2;
  if(londif>0&&latdif>0)
  Az=Az;
  if(londif>0&&latdif<0)
  Az=Az+M_PI;
  if(londif<0&&latdif<0)
  Az=Az+M_PI;
  if(londif<0&&latdif>0)
  Az=Az+(2*M_PI);