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Re: how to calculate distance from pairs of latitude/longitude measurements? [message #65604 is a reply to message #65590]

Wed, 11 March 2009 14:12

natha
Messages: 482
Registered: October 2007

Senior Member

I wrote this small program:

FUNCTION LATLON_DISTANCE, lat1, lon1, lat2, lon2, DEG=deg

IF KEYWORD_SET(deg) THEN BEGIN
lat1=lat1*(!PI/180.)
lon1=lon1*(!PI/180.)
lat2=lat2*(!PI/180.)
lon2=lon2*(!PI/180.)
ENDIF

R=6356.7523 ;; polar radius [km]

a=R*(!PI/2.-lat2)
b=R*(!PI/2.-lat1)

gamma=lon1-lon2

angle=COS(b/R)*COS(a/R)+SIN(b/R)*SIN(a/R)*COS(gamma)
distance=ACOS(angle)*R

RETURN, distance

END

The result is the same as MAP_2POINTS.
I'll use MAP_2POINTS anyway,

thanks

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[Message index]

		Re: how to calculate distance from pairs of latitude/longitude measurements? By: Jeremy Bailin on Thu, 12 March 2009 07:20
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: mankoff on Thu, 12 March 2009 05:02
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: natha on Wed, 11 March 2009 14:12
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: KRDean on Wed, 11 March 2009 13:44
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: David Fanning on Wed, 11 March 2009 13:33
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: natha on Wed, 11 March 2009 13:21
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: Bruce Bowler on Wed, 11 March 2009 13:07
		Re: how to calculate distance from pairs of latitude/longitude measurements? By: natha on Wed, 11 March 2009 12:49

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