angle

I've got a little Problem with the Math.cos() method. I know, I have to convert the angle to Radians before using Math.cos() . But if I just do: System.out.println(Math.cos(Math.toRadians(90)); It outputs: 6.123233995736766E-17 Math.sin() is working well. From trigonometry: sin x ~= x, for small values of x sin x = cos x+pi/2 Because pi/2 can't be represented exactly in IEEE-754 Floating point, it means, that it must be off by some value x, i.e it is represented by pi/2 +- x, where x < the least significant bit in the floating point system. Which in this case is 2^-53 = 1.1102e-16. In this

I'm trying to create a 4D environment, similar to Miegakure 's. I'm having trouble understanding how to represent rotations. The creator of Miegakure wrote this small article explaining he made a class for 4d rotors. http://marctenbosch.com/news/2011/05/4d-rotations-and-the-4d-equivalent-of-quaternions/ How can I implement the functions of this class ? In particular the functions to rotate vectors and other rotors, and getting the inverse ? I would appreciate some pseudocode examples. Thanks a lot to anyone who bothers answering. Solving rotation around arbitrary vector will make you insane in

I'm looking for a code that permits to have this effect on a canvas' stroke . I've already got an animated circular stroke, I only need to get the ANGLE gradient, not linear and not radial. I've got only 3 colours. The existing one is available here (the review rating) A context strokeStyle can be a gradient: // create a gradient gradient = ctx.createLinearGradient(xStart, yStart, xEnd, yEnd); gradient.addColorStop(0.0,"blue"); gradient.addColorStop(1.0,"purple"); // stroke using that gradient ctx.strokeStyle = gradient; Example code and a Demo using a gradient strokeStyle: http://jsfiddle.net

From the functions for MinAreaRect, does it return angles in the range of 0-360 degrees? I am unsure as i have an object that is oriented at 90 degrees or so but I keep getting either -1 or -15 degrees. Could this be an openCV error? Any guidance much appreciated. Thanks I'm going to assume you're using C++, but the answer should be the same if you're using C or Python. The function minAreaRect seems to give angles ranging from -90 to 0 degrees, not including zero, so an interval of [-90, 0). The function gives -90 degrees if the rectangle it outputs isn't rotated, i.e. the rectangle has two

I'm trying to determine the degree size of the field-of-view of a Droid Incredible smartphone's camera. I need to know this value for an application that I'm developing. Does anyone know how I can find out/calculate it programmatically? David Z Unless there's some API call for that (I'm not an Android programmer, I wouldn't know), I would just snap a picture of a ruler from a known distance away, see how much of the ruler is shown in the picture, then use trigonometry to find the angle like this : now you have the two distances l and d from the figure. With some simple goniometry, one can

I need to calculate the angle in degrees between two points for my own Point class, Point a shall be the center point. Method: public float getAngle(Point target) { return (float) Math.toDegrees(Math.atan2(target.x - x, target.y - y)); } Test 1: // returns 45 Point a = new Point(0, 0); System.out.println(a.getAngle(new Point(1, 1))); Test 2: // returns -90, expected: 270 Point a = new Point(0, 0); System.out.println(a.getAngle(new Point(-1, 0))); How can i convert the returned result into a number between 0 and 359? you could add the following: public float getAngle(Point target) { float angle