var degtorad = Math.PI / 180; // Degree-to-Radian conversion function compassHeading2(alpha, beta, gamma , absolute) { var _x = beta ? beta * degtorad : 0; // beta value var _y = gamma ? gamma * degtorad : 0; // gamma value var _z = alpha ? alpha * degtorad : 0; // alpha value var cX = Math.cos(_x); var cY = Math.cos(_y); var cZ = Math.cos(_z); var sX = Math.sin(_x); var sY = Math.sin(_y); var sZ = Math.sin(_z); // Calculate Vx and Vy components var Vx = -cZ * sY - sZ * sX * cY; var Vy = -sZ * sY + cZ * sX * cY; // Calculate compass heading var compassHeading = Math.atan(Vx / Vy); // Convert compass heading to use whole unit circle if (Vy < 0) { compassHeading += Math.PI; } else if (Vx < 0) { compassHeading += 2 * Math.PI; } return compassHeading * (180 / Math.PI); // Compass Heading (in degrees) }but, instead of improving matters, this results in even more wildly erratic behaviour.