Yeah atan2 is a really new concept -- invented maybe 1965 with Fortran, if not before. Pretty much a standard in all language math/ trig suites since then.
http://en.wikipedia.org/wiki/Atan2 On Sep 15, 11:56 am, Pedro Teixeira <[email protected]> wrote: > Geez this is even better than I expected. I was worried with negative > values hence the Math.abs and I wasn't sure how to express in degrees. > > Thank you very much for your answers guys, the atan2 is completely new > to me ;) > > Thanks again > > On Sep 15, 2010, at 5:50 PM, Kostya Vasilyev wrote: > > > > > Um, no. > > > Math.atan2 takes two values, not one. > > > Math.atan2(y2 - y1, x2 - x1) > > > This gives correct result even for x2 and x1 being very close to > > each other. Depending on the sign of y2 - y1 that's either "up" or > > "down". > > > -- Kostya > > > 15.09.2010 20:45, Robert Green пишет: > >> Kostya hit it: > > >> float angleDegrees = Math.toDegrees(Math.atan2((y1 - y2) / (x1 - > >> x2))); > > >> On Sep 15, 11:32 am, Kostya Vasilyev<[email protected]> wrote: > >>> Pedro, > > >>> Java (and pretty much any language's) trig functions work with > >>> angles > >>> expressed in radians. > > >>>http://en.wikipedia.org/wiki/Radian > > >>> To convert to degrees, multiply by 180 / 3,1415926.... (in Java, > >>> that's > >>> Math.PI). Or just call Math.toDegrees. > > >>> Better yet - use Math.atan2 ( difference along Y, different along > >>> X). > >>> This one correctly handles the case of value3-value4 being zero > >>> (or very > >>> close thereof). > > >>> -- Kostya > > >>> 15.09.2010 20:22, Pedro Teixeira пишет: > > >>>> Hi, > >>>> I'm having problems with JAva and trigonometry to calculate a > >>>> direction from a point to a certain point... > >>>> I want to translate this equation to Java-wise: > >>>> tg^-1 = |value1-value2| / |value3-value4| > >>>> And I'd like the result in degrees.. how can I do this? any ideia? > >>> -- > >>> Kostya Vasilyev -- WiFi Manager + pretty widget > >>> --http://kmansoft.wordpress.com > > > -- > > Kostya Vasilyev -- WiFi Manager + pretty widget > > --http://kmansoft.wordpress.com > > > -- > > You received this message because you are subscribed to the Google > > Groups "Android Developers" group. > > To post to this group, send email to [email protected] > > To unsubscribe from this group, send email to > > [email protected] > > For more options, visit this group at > >http://groups.google.com/group/android-developers?hl=en > > Pedro Teixeira > > www.pedroteixeira.org -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
