# Looking For Geodetic Python Software

Cousin Stanley CousinStanley at HotMail.Com
Thu Jun 23 23:32:09 CEST 2005

```| ....
| 1) Given the latitude/longitude of two locations, compute the distance
|    between them.
|
|   "Distance" in this case would be either the straight-line
|    flying distance, or the actual over-ground distance that accounts
|    for the earth's curvature.

# ---------------------------------------------------------------

NewsGroup .... alt.comp.freeware
Date ......... 2003-12-28
Posted_By .... GRL

the formula is as follows:

D = ACos((Sin(LA1)*Sin(LA2)) + (Cos(LA1)*Cos(LA2)*Cos(LO1-LO2))) * r

with:

LA1 / LA2 = latitude position 1 / 2
LO1 / LO2 = longitude 1 / 2
r = radius of earth (~ 6371 km = ~3958,75 miles)
D = distance between locations (in km or miles depending on r)

Source: somewhere below http://geoclassphp.sourceforge.net

# ----------------------------------------------------------------

About 18 months ago I put together a couple of small Python programs
to compute great circle distances from the above formula ....

http://fastq.com/~sckitching/Python/gcircle.py
[ 2.6 kb ]

http://fastq.com/~sckitching/Python/gcircle_dms.py
[ 3.4 kb ]

The first prompts the user for Lat/Long in fixed point degrees.

The second prompts the user of Lat/Long in degrees minutes seconds.

I only checked a few distances known distances at the time,
but they seemed to be OK ....

--
Stanley C. Kitching
Human Being
Phoenix, Arizona

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