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(catalina22)> latitude and longitude to distance formula 
submited by Russell Fri 12 Aug 05 Edited Tue 11 Sep 07 
Formula for the distance between to points given in latitude and longitude
Except for some reason, this formula does not work for me..
I used this (a1,a2,b1,b2) =Latitude,longitude points a,b *IN RADIANS* $r=Radius of earth in desired units:
return sqrt(($a1$b1)**2 + ($a2$b2)**2)*$r;
This formula WILL BE WRONG for large distances, since it does not use a great circle route. (shortest route from NY to japan is via Alaska )
For my needs ( find the closest zip code to a given code) this formula is fine.
Free source of Zip code to latitude and longitude data
Avoid a pitfall that hit me if you use this data in perl. This database has leading zeros on negative values. Perl has a irritating habit of considering these to be Octal numbers ( not decimal numbers) This caused a lot of gibberish output. so do a $x=~s/0//g; on the values before you treat them as numbers.

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