# difference between usage of rostime::Now & toSec for Matlab

Hello everyone,

i have some troubles and hope that you can help me. I want to use the time that i got from ROS in Matalb. First i used the command ros::Time::now(); and i got for each frame a timestamp. And now in matlab, i want to use the difference between the timestamp (eg. timestamp[3] - timestamp [2] or timestamp[4] - timestamp [3]) for further calculations. But the problem is that i always got the value 0 when i calcute the difference. And now i have used the function toSec in ROS. And when i calculate the difference in matlab, i have results # 0, meanings "better results". I have read the wiki http://wiki.ros.org/roscpp/Overview/Time , but it doesnt tell or explain exactly what is the difference between using or working with the ros::Time or toSec ? I hope please that you can better lighten it

Thanks!