Calculation of streamline length (Line object)

Hi everybody,

I explain you my problem : Given a matrix of density current (Jx,Jy), I want to calculate the distance of the streamline for each point of my matrix. To do so, I already write the following code :

 for i=1:ny
    for j=1:nx
        h=streamline(X,Y,Jx,Jy,(j-1)*dx,(i-1)*dy);
        distanceCurrent(i,j)=sum(sqrt(diff(get(h,'Xdata')).^2+diff(get(h,'Ydata')).^2));
    end
end

Where, dx dy are the gridstep and nx ny the number of point. This works well but it takes a lot of time. To improve the running time, I wanted to do the following :

H=streamline(X,Y,Jx,Jy,X,Y)

which gives me an array of line objects. But I cannot do the same as before because get(H(i),'Xdata') for all i returns 0.

Do you have any idea to improve my code or another way to calculate the length of a streamline?

Thank you very much