Applying the Lyapunov exponent to research chaos of economic time series

Investment is an important element that influences the economic, and the quite strong non-linear mechanism can be seen in its rising process. On the basis of the monthly reported data of fixed capital investments in a city, by the Lyapunov exponent calculation method of time series the paper get the maximal Lyapunov exponent of the investment increase. Combining with the former research about the Poincar map and correlation fractal dimension, the conclusion is ulteriorly achieved that the fixed capital investments process of the city is chaotic, and the maximal predictable time of the fixed capital investments is 4 months. A new method to research the complicated economic system is offered.