How can I compute yaw rate from yaw angle?

edit

Hi, I want to find a way to compute the yaw rate using the yaw angle. I have the idea of using the Euler forward method, however, I have encountered some issues like the fact that a full rotation is given by [0-pi, pi-0] and also considering multiple rotations (positives or negatives). The following code only works fine for 1 rotation.

void BebopVel::attitudeCallback(const bebop_msgs::Ardrone3PilotingStateAttitudeChanged &att_msg){

    double yaw = normalize_angle(-att_msg.yaw);
    std::cout << "Curr heading: " << yaw*180/M_PI << std::endl;

    if(!got_first_att_msg_){

        ROS_INFO("got first attitude message");

        prev_attitude_time_ = att_msg.header.stamp;
        prev_yaw_ = yaw;

        got_first_att_msg_ = true;
        return;
    }

    // get current values
    curr_attitude_time_ = att_msg.header.stamp;
    curr_yaw_ = yaw;

    // compute time difference between samples
    ros::Duration delta_t_attitude = curr_attitude_time_ - prev_attitude_time_;
    double ts_attitude = delta_t_attitude.toSec();      // convert from ROS time to seconds

    // compute yaw difference between samples
    double delta_yaw = curr_yaw_ - prev_yaw_;

    // compute yaw rate
    yaw_rate_ = delta_yaw / ts_attitude;

    // assign current values to previous
    prev_attitude_time_ = curr_attitude_time_;
    prev_yaw_ = curr_yaw_;
}


double BebopVel::normalize_angle(double ang){
// Normalizes the angle to be 0 to 2*pi
// It takes and returns radians.

    double norm_ang = fmod(ang, 2.0*M_PI);

    if(norm_ang < 0){
        return norm_ang + 2.0*M_PI;
    }

    return norm_ang;
}

PD: Sorry for my poor English.