interpolation about ship's data

Hello. My sample data is constructed the structure type of Matlab. My data description is as follows; The contents of sample data are ship’s data(date, time, longitude, latitude, speed, course) according to each ship id(MMSI). I have one code about interpolation of ship’s data(date, time, longitude, latitude, speed, course). The time interval of ship’s location is 2~35 second(less than 180 second). Example; The collection time of ship’s data 09:40:56, 09:41:06, 09:41:17... (hour : minute : second) I want to know the ship’s data at 09:40:57~09:41:05, 09:41:07~09:41:16... I want to know the ship’s data per second. So, I solved it the spline interpolation at latitude and longitude data. And, I solved it the linear interpolation at speed and course data. I shared you my sample data on google drive. [login to view URL] Also I attatched one matlab code and one powerpoint for explanation of data and project. I want to solve two problems. First interpolation of course. Course is from 000 degree to 359 degree. For example, when ship turn counterclockwise from 016 degree to 335 degree, result of my code is made by clockwise. 016→019→022→....→335 It is wrong. It should be made such like that 016→010→005→000→355→350→345→340→335. when ship turn clockwise from 336 degree to 007 degree, result of my code is made by counterclockwise. 336→320→310→.300→290→275→...→007 It is wrong. It should be made such like that 336→350→355→000→005→007 Second execution speed improvement of MATLAB code. My code is very slow. That’s why execution speed improvement of my code is key. It takes very long time. I want to improve speed my code with new thinking.