The Haversine formula in Firebird SQL => Calculate distance between two WGS84 Points
Hi,
I think might be helpful, today for a customer i do the Haversine formulas for Firebird Sql as a stored procedure.
This formula allow you to calculate the distance in meter between two WGS84 datum points(degree points of Earth).
You can call the procedure like this:
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SELECT * FROM HAVERSINE_GENERIC(1, 45,474081, 9,179348, 45,456091, 9) |
The result wil be aprox 14Km, the distance from my office and my house aprox.
the parameters of the procedure are:
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CORD_FORMAT integer, --> 0 coordinate expressed in degree, 1 expressed in radiants LAT1 double precision, --> Latitude of Point1 LOG1 double precision, --> Longitude of Point1 LAT2 double precision, --> Latitude of Point2 LOG2 double precision --> Longitude of Point2 |
The procedure code is:
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create procedure HAVERSINE_GENERIC ( CORD_FORMAT integer, LAT1 double precision, LOG1 double precision, LAT2 double precision, LOG2 double precision) returns ( DISTANCE_METER double precision) as declare variable RADIUS double precision; declare variable A double precision; declare variable A0 double precision; declare variable A1 double precision; declare variable A2 double precision; declare variable DISTANCE_KM double precision; declare variable DLON double precision; declare variable DLAT double precision; begin /* LE COORDINATE IN INGRESSO DOVRANNO ESSERE ESPRESSE IN RADIANTI */ if (CORD_FORMAT = 1) then BEGIN LAT1 = LAT1 * (pi()/180); LOG1 = LOG1 * (pi()/180); LAT2 = LAT2 * (pi()/180); LOG2 = LOG2 * (pi()/180); END /* RAGGIO DELLA TERRA IN KM */ radius=6378.137; dlon= (loG2-loG1); dlat= (lat2-lat1); a1 = (sin(dlat/2)); a1 = a1 * a1; a2 = (sin(dlon/2)); a2 = a2 * a2; a= a1 + cos(lat1)*cos(lat2)*a2; distance_km= radius*(2*atan2(sqrt(a),sqrt(1-a))); distance_meter = distance_km*1000; suspend; end |
