A method for interactive simula tion of continuous systems using index mapping functions is presented. State variables, their differential forms and function outputs are represented by elements of a mnemonic set which constitute the building blocks in system modeling. Mapping functions are used to assign each mnemonic a unique pointer to its value location, and also to translate user defined equations into index matrices. Outputs of functions pertaining to any specific problem domain can be easily mapped to the variable list. Procedural details are illustrated with examples of second order sys tems.