[net.aviation] Formula for distance with lat & long

mls@harpo.UUCP (02/13/85)

Some time ago, the formula for calulating the distance and
angle between two points given the long and lat was posted.
Could you repeat that again?

Has anybody had experience with any of the computer services
that offer weather briefings?  What has been the cost?

irv McNair
ATT Bell Labs
Whippany NJ

kanner@tymix.UUCP (Herb Kanner) (02/16/85)

In article <2666@harpo.UUCP> version B 2.10.2 9/18/84; site tymix.UUCP version B 2.10.1 6/24/83; site harpo.UUCP tymix!oliveb!hplabs!hpda!fortune!amdcad!decwrl!decvax!harpo!mls mls@harpo.UUCP writes:
>Some time ago, the formula for calulating the distance and
>angle between two points given the long and lat was posted.
>Could you repeat that again?
>
>
>irv McNair
>ATT Bell Labs
>Whippany NJ

The  following formulae were obtained from  a program library for the Casio
FX-602P programmable calculator.  I believe I checked them out a couple of
years ago.
              -1
	D = 60 cos   {sinN1sinN2 + cosN1cosN2cos(E2-E1)}



               -1 ( sinN2 -sin N1cos(D/60)   )
	theta = cos   (_________________________)
				  (                         )
				  (  sin(D/60)cosN1         )


	Azimuth = theta if sin(E2-E1) >= 0,
	        = 360 - theta if sin(E2-E1) < 0.

N1 and N2 are "north" latitudes.  South ones should be represented by
negative numbers.  Similarly, E1 and E2 are "west" longitudes.  East ones
should be stated as negative.  D is distance in minutes of arc, i.e.
nautical miles.

H. Kanner
Tymnet, Inc.