Compute the curl of a trajectory (identify clockwise or anti-clockwise motion)

Hi everyone,

I want to calculate the curl from single trajectories.

Basically, I want to identify if the trajectory rotates clockwise of anti-clock wise and measure the rotation speed.

I use something like the below:

x = data(:,1);

y = data(:,2);

u = data(:,3);

v = data(:,4);

V = [u v];

R = [x y];

curlRes = curl(V,R);

The result is 0 everywhere.

I also tried [curlz,cav] = curl(x,y,u,v) and it gives the follwoing error

'Index in position 1 is invalid. Array indices must be positive integers or logical values.'

the vectors u,v contain negative values as they indicate the direction of the velocity

Thank you