> Jamey Saunders wrote: > > I have a bit of a problem with a pretty complicated mathematical > > expression. Basically, I'm trying to determine the initial heading > > between two points on the globe using latitude and longitude of the > > two points. I already know the distance between the two ($miles). > > > > Here's the expression: > $Hdg=2*M_PI-acos((sin($lat2)-sin($lat1)*cos($miles))/(sin($miles)*cos($lat1))); > > > > When I echo $Hdg, I see: > > > > -1.#IND > > > > If the expression was working, I should see something like 134.9 for > > the following latitude/longitude combinations: > > > > $lat1 = 33.9780761 > > $lon1 = -83.9623772 > > $lat2 = 32.1950556 > > $lon2 = -81.8695556 > > $miles = 172.7381359 > > > > I can't find any references to what #IND means, so if anyone out there > > has any ideas, I'd be grateful. > > > > -JS
--- Brian Cummiskey <[EMAIL PROTECTED]> wrote: > > Only thing i can thinkg of off the top of my head is that you are trying > to plug in degrees and minuets, but the sin,cos, and other trig > functions in php take on a parameter in radians-- not degrees. Degrees vs. radians can certainly be a factor. Make sure you are giving the functions a value in radians. Also, you have this item: 2*M_PI Have you defined a constant called M_PI or do you expect it to be a variable? Here are some links which may be helpful for determing the bearing (or heading) between two latitude and longitude points: http://www.movable-type.co.uk/scripts/LatLong.html http://mathforum.org/library/drmath/view/55417.html This sounds like a Google Map application :) James _____ James D. Keeline http://www.Keeline.com http://www.Keeline.com/articles http://Stratemeyer.org http://www.Keeline.com/TSCollection http://www.ITeachPHP.com -- Free Computer Classes: Linux, PHP, etc. Fall Semester Begins Sep 7 -- New Classes Start Every Few Weeks. ------------------------ Yahoo! Groups Sponsor --------------------~--> Get Bzzzy! (real tools to help you find a job). Welcome to the Sweet Life. http://us.click.yahoo.com/A77XvD/vlQLAA/TtwFAA/HKFolB/TM --------------------------------------------------------------------~-> Community email addresses: Post message: [email protected] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED] Shortcut URL to this page: http://groups.yahoo.com/group/php-list Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/php-list/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
