Plotting prices as a function of time

Im trying to understand data from a data file. If I have

d∆t(t) = x(t + ∆t) − x(t) , where ∆t is the trading days difference and x is price

If I assign t as

numberofdays=10;  %and use 1 to number of days as a time axis
t=1:lenghth(numberofdays)  %where number of days is the are the number of trading days in the data 
x=[5;4;3;4;5;6;7;8;5;3];  %prices

. For each ∆t I should get a new time seriesd ∆t that is of length numberofdays−∆t, How would I plot d1(t) and d2(t) as a function of time.