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HaversineDistance ( latx ; lony ; laty ; lony ; units )

compute shortest distance

  Average rating: 4.4 (27 votes) Log in to vote

john renfrew - Show more from this author attitude

  Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

/* * HaversineDistance * shortest distance between two points on great circle * if units is empty returns imperial in miles and yds, else metric in km * 15_02_03 J Renfrew */ Let ( [ _R = 6372.8 ; _dLat = Radians ( laty - latx ) ; _dLon = Radians ( lony - lonx ) ; _lati = Radians ( latx ) ; _latj = Radians ( laty ) ; _a = Sin ( _dLat / 2 ) * Sin ( _dLat / 2 ) + Sin ( _dLon / 2 ) * Sin ( _dLon / 2 ) * Cos ( _lati ) * Cos ( _latj ) ; _c = 2 * Asin ( Sqrt ( _a ) ) ; _M = _R * _c * .621371192 ] ; Case ( IsEmpty ( units ) ; Int ( _M ) & " mi " & Round ( ( _M - Int ( _M ) ) * 1760 ; 2 ) & " yds" ; Round ( _R * _c ; 3 ) & " km" ) ) Click to copy

The haversine formula is an equation important in navigation, returning great-circle distances between two points on a sphere from their longitudes and latitudes.

 

Comments

		Tim Anderson, Tim Anderson Group Mar 4, 2015
Just to repay the compliment John, you a typo or 2! HaversineDistance ( latx ; lony ; lat y ; lony ; units ) should be HaversineDistance ( latx ; lonx ; laty ; lony ; units )? Tim

		john renfrew, attitude Mar 4, 2015
Tim Well spotted Mr Darcy... Jeremy Bante's custom function uses the more complex Andoyer-Lambert-Thomas method if the coordinates are in the WGS84 coordinate system, and is more accurate, but this is within 99.98% of that, so for use in short distance calculations is as effective https://github.com/jbante/FileMaker-Techniques/blob/master/CustomFunctions/Location/LocationDistanceValues.fmfn

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