On Sun, Jul 13, 2008 at 12:43 AM, Patrick Walker <[EMAIL PROTECTED]> wrote: > Yes, I'm aware that you need to supply radians. > > Everthing appears to be fine when going from 0 to 45 degrees but at 90 > degrees, the tangent returns -22877334. > > I've even tried doing the tan(x) = sin(x) / cos(x) approach.
Floating point arithmetic is inherently imprecise. Atan(-22877334) is equal to pi/2 to within roughly eight decimal places or approximately 25 bits. I'm not sure what the guaranteed accuracy of that function is supposed to be, and this does seem to be a bit excessive, but on the other hand you are right next to a singularity in the function. Depending on how you're generating "90 degrees", that could be introducing further inaccuracy. These aren't mathematically ideal functions, so you can't expect them to behave as such. This goes particularly when using them in a region of extreme behavior such as this. In particular you should never expect a function which is undefined or infinite at a single point and defined and finite in all the regions immediately adjacent to that point to produce an undefined or infinite result, unless that point is a value which can be represented precisely, such as "0". 90 degrees cannot be represented precisely when converted to radians, so you'll never get NaN or INFINITY out of the tan() function. If you still think they're misbehaving, I suggest posting the code you're using. It's difficult to provide more specific help with no code. Mike _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
