If you want to shift your data by an integer number of samples you can do something like this (here I'm just shifting y2, and plotting it but you can do something similar with your m_test calculation):
plot(t,y1,t1(1:end-9),y2(10:end))
If you can not just shift by an integer number of samples, you can first interpolate the data so that the shift you want will be an integer number of samples. The MATLAB function interp1 should be helpful for this.
