Computing Difference Between two timeseries objects.

I have two timeseries objects Ts and Ts2. They initially were sampled at different time instants, so I synchronised them using synchronize function. Now I need to compute the difference ( in order to calculate error in Data). How do I do this?. This i what I tried. When I do this, it is showing error: OUT of MEMORY.

[Ts,Ts2]=synchronize(Ts,Ts2,'union');
temp=Ts.Data(1:size(Ts2.Data))-Ts2.Data;