The automatic programming of simulations

This is a special reprint of one of the classic papers on computer simulation, written by the late K D Tocher. He wrote: The effective extension of simulation techniques demands the use of computers and the provision of automatic coding aids. This paper outlines a programme of work which has contributed to this extension by devising a simulation language which can be subjected to automatic coding by a Ferranti ‘Pegasus’ Computer. A master program has been written which executes the coded statements within a common structure which applies to all simulation experiments. The structure depends on representing the plant as a collection of machines in various states. A change of state of any machine is an ‘event’, and the program predicts successive events and changes the plant state accordingly. The predictions are based on a series of logical rules concerning the necessary states of machines for processes to commence, and uses sampling techniques to determine their conclusion. The simulation language is designed for describing the logical rules. Experience so far with this scheme indicates a substantial saving of time in writing and testing computer simulations, with no severe loss of running speed. It has been found flexible enough to deal with a wide range of different problems.