PURPOSE: To impart the capacity of controlling the input variable of a model preparing software to a data processing system.

CONSTITUTION: This system consists of the model preparing software 10 capable of defining a model with plural input variables, a changing means 40 for deciding the initial value of the input variable, a model output means 20 generating the driving signal of an output device 30 based on the state of the model depending on the value of the input variable and a signal supplying means for sending the generated driving signal to the output device 30. The changing means 40 randomly adjusts the value of the input variable within a prescribed limit, inserts the value adjusted for changing the state of the model into the model preparation software 10 and decides the new set of the input variable in response to judging information inputted by a user. The data processing system is programmed to repeat the generation of the driving signal selected number of times based on the changed model and to repeat the generation of the series of driving signals based on the new set of the initial values.