function bd_decrypt(bd_lon,bd_lat) { var X_PI = Math.Pi * 3000.0 / 180.0; var x = bd_lon - 0.0065; var y = bd_lat - 0.006; var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * X_PI); var theta = Math.atan2