Preferably in R or Matlab

Consider a shop selling an infinitely divisible product. It gets units of the product from the factory after an order to do so, it stores these, and it sells to customers who demand certain amounts of the product. The shop can accomodate at most S units of the product. Time is periodic (discrete): n=0,1, At the beginning of period n the height of the inventory is Xn. The demand during period n is random Dn. Demand is immediately fullfilled if available. Demand that cannot be fulfilled is lost. Thus, at the end of period n the inventory is Xne=(XnDn)+. If Xne