Calculating Distances using Latitude and Longitude (Haversine Formula)

[GeorgeMcGinn]

Here is a function that calculates the haversine, or distances between two points using the Latitude and Longitude of each location.

Useful when programming GPS coordinates and you need to know how far you are from your destination, or to calculate the distance between two cities, as in the code wrapping this function.

The function calculates Kilometers, but has the option (passed as UNIT$) to calculate in Miles or Nautical Miles.

George.

Code: Select all

'*** Haversine Function
'*** George McGinn, January 2017


'*** LAT/LONG For Venice, FL
Lat1=27.07
Lon1=-82.44

'*** LAT/LONG For Sarasota, FL
Lat2=27.40   
Lon2=-82.55

'*** Units: K=kilometers  M=miles  N=nautical miles
Unit$ = "M"	

Result=Haversine(Lat1,Lon1,Lat2,Lon2,Unit$)

PRINT "The Distance From Venice, FL to Sarasota, FL in Miles is: "&Result

DEF Haversine(Lat1,Lon1,Lat2,Lon2,Unit$)
    PI=3.14159265358979323846
    Radius=6378.137
    Lat1=(Lat1*PI/180)
    Lon1=(Lon1*PI/180)
    Lat2=(Lat2*PI/180)
    Lon2=(Lon2*PI/180)
    DLon=Lon1-Lon2
    Answer=ACOS(SIN(Lat1)*SIN(Lat2)+COS(Lat1)*COS(Lat2)*COS(DLon))*Radius

    IF UNIT$="M" THEN Answer=Answer*0.621371192
    IF UNIT$="N" THEN Answer=Answer*0.539956803

  RETURN Answer
ENDDEF

[rbytes]

Very useful. Thanks, George.

[GeorgeMcGinn]

Sorry, one thing I did not point out is that the answer without the modifications of the if statements is always in kilometers.

So in my print statement, you need to change "miles" to the unit you select. (Even though it only checks for M or N, you can put a K for kilometers or any other value.

George.