DistanceGeoCoord ( Lat1deg ; Lat1mm ; Lat1ss ; Lon1deg ; Lon1mm ; Lon1ss ; Lat2deg ; Lat2mm ; Lat2ss ; Lon2deg ; Lon2mm ; Lon2ss ; U ; Version )

Measure the distance between two geographic coordinates

Average rating: 4.4 (36 votes) Log in to vote

Edward_Souza
n/a
n/a

Sample input:

DistanceGeoCoord ( 50 ; 6 ; 44 ; 8 ; 44 ; 5 ; 52 ; 31 ; 20 ; 13 ; 17 ; 51 ; Km ; Radial )

Sample output:

/* Distance between Frankfurt and Berlin

(If "U" = Km) 418.34
(If "U" = Mi) 259.95

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

/*-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
          Custom Function DistanceGeoCoord
-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_

Abstract: DistanceGeoCoord ( Lat1deg ; Lat1mm ; Lat1ss ; Lon1deg ; Lon1mm ; Lon1ss ; Lat2deg ; Lat2mm ; Lat2ss ; Lon2deg ; Lon2mm ; Lon2ss ; U ; Version )

Developer: Edward Souza (edusouza@mac.com)

Source: Custom Function DistanceGeoCoord is a FileMaker Pro 10 Advanced Custom
Function based on formulae gathered from <http://mathforum.org/>.

About this Custom Function:
This is a rather complete function to measure the linear distance between two
geographic coordinates in units such as Nautic Miles,  Miles, Kilometers, and
Meters.
Because most Geographic Coordinates' calculae are based on a GIS standard
known as Decimal Degrees (DD) -- and since coordinates themselves are expressed
in a different format (DMS, or Degrees, Minutes, and Seconds) -- a conversion
between them is necessary.
This custom function does it, depending on how data are inserted in parameters
Latitude 1 (Lat1deg, Lat1mm, and Lat1ss), Longitude 1 (Lon1deg, Lon1mm, and
Lon1ss), Latitude 2 (Lat2deg, Lat2mm, and Lat2ss), and Logitude 2 (Lon2deg,
Lon2mm, and Lon2ss).
For example: if parameter Lat1deg has data inserted but Lat1mm and Lat1ss are
left empty, the function will recognize the first as DD and treat it as such.
The same will happen with the other coordinates.
Thus you may mix both standards -- e.g. Coordinates 1 as DMS and Coordinates 2
as DD. This is quite handy if you are working with two databases, each based
on a standard.
According to SI and GIS, Northern and Eastern coordinates are understood as 
"positive", while Southern/Western ones are deemed as "negative". Hence, a set
of coordinates such as S 9º48'40'' W 66º 53' 02'' shall be written as -9 48 40
and -66 53 02.

Parameter "U" stands for "Unit", and accepts one of the following values:
"Km" (for "Kilometers")
"m" (for "meters")
"Mi" (for "Miles")
"NMi" (for "Nautical Miles").
Since these values refer to the radius of the earth at the equator, you may
use any other. Just add them to the "R" variables.

Parameter "Version" gives the function the ability to isolate or not the
coordinates. One of these values -- Radians or Degrees -- shall be used.

I hope you enjoy it.

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
          Custom Function DistanceGeoCoord
-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_*/

Let ( [

//if latitudes and longitudes are not in Decimal Degrees (DD), these formulae will convert them to their decimal equivalencies

Lat1Dec =
	If( 
	not IsEmpty( Lat1mm ) and not IsEmpty( Lat1ss ); 
	GetAsNumber( Lat1deg + GetAsNumber( Lat1mm / 60 ) + GetAsNumber( Lat1ss / 3600 ) ); 
	GetAsNumber( Lat1deg )
	); 
Lon1Dec =
	If( 
	not IsEmpty( Lon1mm ) and not IsEmpty( Lon1ss ); 
	GetAsNumber( Lon1deg + GetAsNumber( Lon1mm / 60 ) + GetAsNumber( Lon1ss / 3600 ) ); 
	GetAsNumber( Lon1deg )
	); 
Lat2Dec =
	If( 
	not IsEmpty( Lat2mm ) and not IsEmpty( Lat2ss ); 
	GetAsNumber( Lat2deg + GetAsNumber( Lat2mm / 60 ) + GetAsNumber( Lat2ss / 3600 ) ); 
	GetAsNumber( Lat2deg )
	); 
Lon2Dec =
	If( 
	not IsEmpty( Lon2mm ) and not IsEmpty( Lon2ss ); 
	GetAsNumber( Lon2deg + GetAsNumber( Lon2mm / 60 ) + GetAsNumber( Lon2ss / 3600 ) ); 
	GetAsNumber( Lon2deg )
	); 

//Version "Radian"
Lat1Rad = Radians( Lat1Dec ); 
Lon1Rad = Radians( Lon1Dec ); 
Lat2Rad = Radians( Lat2Dec ); 
Lon2Rad = Radians( Lon2Dec ); 
dLonRad = Lon2Rad - Lon1Rad; 
ERad = Acos( ( Sin( Lat1Rad ) * Sin( Lat2Rad ) ) + ( Cos( Lat1Rad ) * Cos( Lat2Rad ) * Cos( dLonRad ) ) ); 

//Version "Degree"
dLonDec = Lon2Dec - Lon1Dec; 
EDeg = Acos( ( Sin( Radians( Lat1Dec ) ) * Sin( Radians( Lat2Dec ) ) ) + ( Cos( Radians( Lat1Dec ) ) * Cos( Radians( Lat2Dec ) ) * Cos( Radians( dLonDec ) ) ) ) ; 

//Earth radius in several units (others may be added)

R = 
	Case( 
	U = "Km"; 6378.137; // radius of the earth in kilometers
	U = "m"; 6378137; // radius of the earth in meters
	U = "Mi"; 3963.191; // radius of the earth in statute miles
	U = "NMi"; 3437.74677 // radius of the earth in nautical miles
	)
]; 

Case( 

	IsEmpty( Lat1deg ) or IsEmpty( Lon1deg ) or IsEmpty( Lat2deg ) or IsEmpty( Lon2deg );
	"Error - Missing Geographic Data"; 

	//If you added a new value, place its acronym here as well
	IsEmpty( U ) or ( U ≠ "Km" and U ≠ "m" and U ≠ "Mi" and U ≠ "NMi" ); 
	"Error - Missing (or Wrong) Unit"; 

	IsEmpty( Version ); 
	"Error - Missing Version"; 

	Version = "Degrees"; EDeg * R; 

	Version = "Radians"; ERad * R

	)
)

This is a rather complete and flexible custom function on measuring linear distances between two geographic coordinates, for it allows the user/developer to insert coordinate values in DMS (Degrees, Minutes, and Seconds) and DD (Decimal Degrees). Yet, it goes a bit further on flexibility , for it permits the calculation of angle functions either in Degrees or Radians.
The function itself is quite straightforward and easy to understand. Please refer to the text in the beginning and inside-function notes for deeper information.

Comments

		Gil Jean, Paris Fr Feb 26, 2010
hello, edward, this is nice function. thanks for sharing it. i would like to know how to add different measures in this function, and how to do it. thank you, jean

		Edward Souza, Sao Paulo, Brazil Feb 26, 2010
Salut, Gil Jean, Let us say you need to measure the linear distance between two coordinates in inches. The first thing to do give this unit a "name" or an acronym (for the sake of an example, let us call it "In") then include it plus the radius of earth on the Equator (which, by my calculations, is 251107782.481124 inches) to the "R" variables. When done, "R" shall look like this: R = Case( U = "Km"; 6378.137; // radius of the earth in kilometers U = "m"; 6378137; // radius of the earth in meters U = "Mi"; 3963.191; // radius of the earth in statute miles U = "NMi"; 3437.74677; // radius of the earth in nautical miles U = "In"; 251107782.481124 // radius of the earth in inches ) The next step is to include "In" to the validation parameter below "R". This would then look like this: //If you added a new value, place its acronym here as well IsEmpty( U ) or ( U â‰ "Km" and U â‰ "m" and U â‰ "Mi" and U â‰ "NMi" and U â‰ "In" ); "Error - Missing (or Wrong) Unit"; That's this simple. I hope I could've been of any help. Edward

		Ben, realseeds Mar 7, 2010
Hello Edward, What is the difference between the 2 parameter "Version": Radians or Degrees. What do you mean by "isolate or not the coordinates"? Thanks Ben

Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

DistanceGeoCoord ( Lat1deg ; Lat1mm ; Lat1ss ; Lon1deg ; Lon1mm ; Lon1ss ; Lat2deg ; Lat2mm ; Lat2ss ; Lon2deg ; Lon2mm ; Lon2ss ; U ; Version )

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