haversin function

haversin.js

    var R = 6371 //km 
    function sinsqr(x,x1){
     difference =(x1-x)*Math.PI/180;
     result=Math.pow(Math.sin( difference /2)  ,2)
     return result;
    }
    function d2tan(a){
       result= 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
       return result;
    }
    /* not işlemler radyan cinsinden olmak zorunda */
    function haversine(lat1,long1,lat2,long2){
    newlat1=lat1 * Math.PI/180;
    newlat2= lat2 * Math.PI/180;
    newsinsqr1=sinsqr(long1,long2);
    newsinsqr2=sinsqr(lat1,lat2);
    result=Math.asin( newsinsqr1+newsinsqr2 * newlat1* newlat2);
    calcd2tan=  d2tan(result);
    finalresult=R *  calcd2tan;
    return finalresult;
    }