Euclidean distance/time between differential equations

So I want to show sensitivity to initial conditions in differential equations. So I want to graph time/distance between similar equations but with different initial conditions.When initial conditions are same I don't get any errors, but whenever I try to change one of the initial conditions, it says: Error using - Matrix dimensions must agree.

Error in startrealchua2 (line 4) Z = sqrt((k(:,1)-y(:,1)).^2+(k(:,2)-y(:,2)).^2+(k(:,3)-y(:,3)).^2) ;