RE: The Great Circle

["Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>]

How exact do your #s need to be? I assume you're probably working on Lat
and Long from zip codes, so you're not perfectly accurate anyway. I've
found that that math can be done as:

SQRT( (69.1*(lat1-lat2))^2 + (53*(long1-long2))^2 )

It's not as exact as the "real" formula, but it's w/in several miles at
the worst, and since a zip code is usually larger than several miles,
and we're talking "as the crow flies" not driving distance anyway, the
error is meaningless.

-Walden


------------
Walden H Leverich III
President & CEO
Tech Software
(516) 627-3800 x11
WaldenL@xxxxxxxxxxxxxxx
http://www.TechSoftInc.com 

Quiquid latine dictum sit altum viditur.
(Whatever is said in Latin seems profound.)
 
-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Bruce Odum
Sent: Wednesday, August 18, 2004 3:14 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: The Great Circle

I am trying to convert the formula for taking two deg mm ss convert them
to
dec and calc the distance from the two points.   I am having some
problems
making this formula work I have posted the formula as an image below.  I
am
trying to use the ceessacs but its returns a error every time. The sin
and
cos works fine.  I am converting all my dec. to float.  Has anyone ever
translated this formula to free or fixed and made it work.
dACS PR 8f Extproc('CEESSACS')

din 8f value