[calc_distance]

Description

This tag will calculate the distance between two points defined by latitude and longitude in miles with an optional parameter to return kilometers. Internally uses an implementation of the Haversine formula to account for curvature of the earth.

Sample Usage

local('curr_coords' = pair(51.027576,-114.058891))
local('dest' = pair(51.011760, -114.066260))
calc_distance(
       #curr_coords->first, 
       #curr_coords->second, 
       #coord->first, 
       #coord->second
)



Returns:
1.172478

Source Code

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define calc_distance(curr_lat::decimal, curr_lon::decimal, dest_lat::decimal, dest_lon::decimal, meas='m') => {
	//provide current location and destination as latitude and longitude as decimal
	//optionally provide meas value of 'k' to return kilometers
	
	local(distance = (
		(
		(
			(#curr_lat * pi / 180)->sin * (#dest_lat * pi / 180)->sin 
			+ (#curr_lat * pi / 180)->cos * (#dest_lat * pi / 180)->cos * 
			((#curr_lon - #dest_lon) * pi / 180)->cos
		)->acos * 180 / pi
		) * 60 * 1.1515
		))
	#meas == 'k' ? return #distance*1.609344 | return #distance
	//return #distance
}

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