The problem is int center = radius which you are setting int radius = 576. This doesn’t make sense as surely you are rotating about a point that should have an x and y location. Given you are rotating around the origin the center x and y should both be 0 not 576. So, given … Read more
Here’s the guaranteed fastest possible sine function in C++: double FastSin(double x) { return 0; } Oh, you wanted better accuracy than |1.0|? Well, here is a sine function that is similarly fast: double FastSin(double x) { return x; } This answer actually does not suck, when x is close to zero. For small x, … Read more
Computer Approximations by Hart. Tabulates Chebyshev-economized approximate formulas for a bunch of functions at different precisions. Edit: Getting my copy off the shelf, it turned out to be a different book that just sounds very similar. Here’s a sin function using its tables. (Tested in C since that’s handier for me.) I don’t know if … Read more
function rotate(cx, cy, x, y, angle) { var radians = (Math.PI / 180) * angle, cos = Math.cos(radians), sin = Math.sin(radians), nx = (cos * (x – cx)) + (sin * (y – cy)) + cx, ny = (cos * (y – cy)) – (sin * (x – cx)) + cy; return [nx, ny]; } … Read more
It seems you are measuring distance (R) in meters, and bearing (theta) counterclockwise from due east. And for your purposes (hundereds of meters), plane geometry should be accurate enough. In that case, dx = R*cos(theta) ; theta measured counterclockwise from due east dy = R*sin(theta) ; dx, dy same units as R If theta is … Read more
The atan2 function eases the pain of dealing with atan. It is declared as double atan2(double y, double x) and converts rectangular coordinates (x,y) to the angle theta from the polar coordinates (r,theta) So I’d rewrite your code as public static double angleBetween2Lines(Line2D line1, Line2D line2) { double angle1 = Math.atan2(line1.getY1() – line1.getY2(), line1.getX1() – … Read more
The coordinates of the center point (cx,cy) of a line segment between points (x1,y1) and (x2,y2) are: cx = (x1 + x2) / 2 cy = (y1 + y2) / 2 In other words it’s just the average, or arithmetic mean, of the two pairs of x and y coordinate values. For a multi-segmented line, … Read more
Given a radius length r and an angle t in radians and a circle’s center (h,k), you can calculate the coordinates of a point on the circumference as follows (this is pseudo-code, you’ll have to adapt it to your language): float x = r*cos(t) + h; float y = r*sin(t) + k;
ApFloat is a library which contains arbitrary-precision approximations of trigometric functions and non-integer powers both; however, it uses its own internal representations, rather than BigDecimal and BigInteger. I haven’t used it before, so I can’t vouch for its correctness or performance characteristics, but the api seems fairly complete.