Efficient Coding of the Minimum Image Convention

The computation of distances between interactions sites while observing the minimum image convention is one of the most frequently performed operations in computer simulations of fluids. In this work several ways of encoding the minimum image convention are discussed and their performances on different computers compared. It turns out that the optimal choice for the algorithm depends on the computer type as well as the optimization level of the compiler, and that a well adapted algorithm can achieve a significant reduction of the computation time.