How about this script: http://www.hotscripts.com/Detailed/54549.html ? If you have a look at the bottom of the page, you'll also notice that this script is available for different programming platform.
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Regards,
Ahmad Permessur
Team HotScripts
Thank you for your reply. But now the problem is that I am not resident of US,Canada or Mexico and I don't know how to find latitude/longitude of two points!