A note on economic order quantity models for deteriorating items under stock dependent selling rate

In 1995, Padmanabhan and Vrat presented inventory models for deteriorating items with stock dependent selling rate and derived the profit functions without backlogging and with complete backlogging. First, this paper develops the necessary and sufficient conditions of the existence and uniqueness of the optimal solutions of the profit per unit time functions without backlogging and with complete backlogging. Second, this paper explains that it is appropriate to use the Newton–Raphson method to find the optimal solutions of the profit functions per unit time in both situations modelled.