We have developed a mathematical tool able to track irreversible processes in magnetic systems described by the Stoner-Wohlfarth model, under any applied field history. A graphic representation is worked out that accounts for interactions, and turns out to be an extension of the one operating in the Preisach model. The response to alternating and rotating magnetizing fields have been investigated in detail. We have found a strategy in dealing with hysteretic memory effects which speeds the computational work needed to get the materials magnetization. This approach can represent a suitable tool aimed at estimate the energy loss and entropy production in magnetic systems.