private void computeOrientation() {
    if (SensorManager.getRotationMatrix(m_rotationMatrix, null,
                                        m_lastMagFields, m_lastAccels)) {
        SensorManager.getOrientation(m_rotationMatrix, m_orientation);

        /* 1 radian = 57.2957795 degrees */
        /* [0] : yaw, rotation around z axis
         * [1] : pitch, rotation around x axis
         * [2] : roll, rotation around y axis */
        float yaw = m_orientation[0] * 57.2957795f;
        float pitch = m_orientation[1] * 57.2957795f;
        float roll = m_orientation[2] * 57.2957795f;

        /* append returns an average of the last 10 values */
        m_lastYaw = m_filters[0].append(yaw);
        m_lastPitch = m_filters[1].append(pitch);
        m_lastRoll = m_filters[2].append(roll);
        TextView rt = (TextView) findViewById(R.id.roll);
        TextView pt = (TextView) findViewById(R.id.pitch);
        TextView yt = (TextView) findViewById(R.id.yaw);
        yt.setText("azi z: " + m_lastYaw);
        pt.setText("pitch x: " + m_lastPitch);
        rt.setText("roll y: " + m_lastRoll);
    }
}

if (SensorManager.getRotationMatrix(m_rotationMatrix, null,
                                    m_lastAccels, m_lastMagFields)) {