a list of two date frames, the simulation and the metrics.
Details
The Function takes a demand vector, mean of demand ,sd,lead time and
requested service level to simulate and inventory system,
orders are lost if inventory level is less than requested demand, also ordering is made at
day t+1, metrics like item fill rate and cycle service level are calculated.
the order up to level is calculated based on the review period,lead time and Poisson distribution .
# NOT RUN {Periodic_review_pois(demand=rpois(80,6),lambda=6,leadtime=5,service_level=0.95,
Review_period =9,
shortage_cost= FALSE,inventory_cost=FALSE,ordering_cost=FALSE)
# }