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Re: how to calculate distance from pairs of latitude/longitude measurements? [message #65609 is a reply to message #65608]

Wed, 11 March 2009 13:07

Bruce Bowler
Messages: 128
Registered: September 1998

Senior Member

On Wed, 11 Mar 2009 12:49:41 -0700, llo wrote:

> I found MAP_PROJ_FORDWARD function to convert lat/lon to cartesian
> coordinates. So, calculate the distance between 2 cartesian points it's
> eaasy.
>
> The problem is when I use this function. The following problem ocurs:
>
> alb_cart=MAP_PROJ_FORWARD(-73.83,42.70) % MAP_PROJ_FORWARD: Value of
> Projection index is out of allowed range. % Execution halted at: $MAIN$
>
> (-73.83,42.70) are a valid lat/lon coordinates of station situated in
> Albany, USA.
> MAP_STRUCTURE is required to use this function (MAP_PROJ_FORWARD) but I
> don't know which mapping projection use.
>
> Any suggestions !?

Eqn's for doing anything you want with lats and longs can be found here...

http://williams.best.vwh.net/avform.htm

Converting them to IDL is left as an exercise for the reader (warning -
be careful with your signs if you use his formulae, the fly-boys appear
to be out of step with the rest of the world :-)

Bruce

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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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