Great Circle Distance Function - Haversine Formula

This function computes the great circle distance in Kilometers using the Haversine formula distance calculation.

If you want it in miles, change the average radius of Earth to miles in the function.

create function dbo.F_GREAT_CIRCLE_DISTANCE
(
@Latitude1 float,
@Longitude1 float,
@Latitude2 float,
@Longitude2 float
)
returns float
as
/*
fUNCTION: F_GREAT_CIRCLE_DISTANCE

Computes the Great Circle distance in kilometers
between two points on the Earth using the
Haversine formula distance calculation.

Input Parameters:
@Longitude1 - Longitude in degrees of point 1
@Latitude1 - Latitude in degrees of point 1
@Longitude2 - Longitude in degrees of point 2
@Latitude2 - Latitude in degrees of point 2

*/
begin
declare @radius float

declare @lon1 float
declare @lon2 float
declare @lat1 float
declare @lat2 float

declare @a float
declare @distance float

-- Sets average radius of Earth in Kilometers
set @radius = 6371.0E

-- Convert degrees to radians
set @lon1 = radians( @Longitude1 )
set @lon2 = radians( @Longitude2 )
set @lat1 = radians( @Latitude1 )
set @lat2 = radians( @Latitude2 )

set @a = sqrt(square(sin((@lat2-@lat1)/2.0E)) +
(cos(@lat1) * cos(@lat2) * square(sin((@lon2-@lon1)/2.0E))) )

set @distance =
@radius * ( 2.0E *asin(case when 1.0E < @a then 1.0E else @a end ))

return @distance

end


Edit: corrected spelling


CODO ERGO SUM