normalizeAngle180 function
Normalizes degrees into the range (-180, 180].
Useful for shortest-rotation calculations where the sign indicates direction.
Example:
normalizeAngle180(270); // -90.0
Implementation
double normalizeAngle180(double degrees) {
double d = degrees % 360;
if (d > 180) d -= 360;
if (d < -180) d += 360;
return d;
}