I'm checking for zeros on all my divides, so hopefully that won't be a problem...
Thanks, JS Emily Berk wrote: >One other thing which may be a problem once you've surmounted this one: > >For certain combinations of the distance, the latitude and longitude, the >product of those sin and cos functions that you are dividing by might equal 0. > >-- Emily > >At 01:26 PM 8/30/05 -0700, you wrote: > > >>>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. >> >> >> >>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 >> >> >> >> >> >> > > > > > >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 > > > > > > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Fair play? Video games influencing politics. Click and talk back! http://us.click.yahoo.com/T8sf5C/tzNLAA/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/
