The update process is characterized by parallelism, homogeneity, and locality.
Parallelism means that all the cells are updated at the same time, in lock-step synchronization.
There is, however, no intrinsic reason why CAs should not have state values characterized as one or even several continuous-valued numbers. Looking at such continuous-valued CAs to some extent duplicates work which numerical analysts have already done under the name of finite difference method simulations. The CA framework also provides a conceptual language for discussing a simulation's behavior after instability sets in. For our continuous-valued CAs we let each cell be a small data structure which contains two floating point numbers that we call U and V . These are to stand for the intensity and velocity, that is, U stands for u and V stands for .