On the Huygens principle in the Puu model

We consider the macroeconomic model of T. Puu, describing the fluctuations of gross income in a given region. With a special combination of savings and investment rates, income deviations will take place only for a finite period of time, after which the income will return to a stationary state. This effect is known in mathematical physics as the Huygens principle. We investigated this model using statistical methods of data analysis. The obtained results suggest that the Huygens effect hypothesis in certain historical periods of the Russian economy is plausible. We have also considered the structure of the set of stationary zeros for nontrivial solutions to a stationary equation.