PURPOSE: To surely detect increase in activity by simulating a statistical thermodynamics reaction speed logic process over prescribed independent status variables according to a programmed state change.

CONSTITUTION: The interval of independent state variables IV (time) to be simulated is inputted (S2). A programmed state variable PV (temperature) being the IV is entered (S4). A dependent state variable DV (reaction speed) is calculated as a function of the PV variable with respect to a current IV (S8). In this case, individual reaction probabilities are added to obtain the total reaction speed and a time step is calculated as a probability by calculation of a time stop using its reciprocal (S10). The current IV is updated by the addition of the time step (S12). One event is selected according to a conventional stochastic simulation and the simulation is updated (S13). When the end of the interval IV comes, the simulation is finished (S16).