First: Are you sure your T vector is in seconds? If so, your time list covers about 48 milliseconds around 01-Jan-1904 11:41:29. It makes more sense if T is in days since 1904-01-01.
Anyway, here is a way to do it:
dt = datetime(1904,1,1) + T;
dv = datevec(dt);
I recommend to work with datetime objects, which are very flexible. For instance, the time axis adustst automatically when you zoom in plots.