The General EOQ model with increasing demand and costs

Assume that one day's demand for products, one day's holding cost per one unit of product and setup cost are expressed as increasing functions of time. Moreover assume that we are given a time interval under these circumstances. The aim of our study is to find the optimal inventory policy which minimizes the total inventory cost required during this interval. How often orders are placed during this interval and how much is ordered at each ordering time point are our concerns. The techniques of DP are introduced to solve this problem.