Mironenko reflecting function

The Reflecting Function $\,F(t,x)$ of the system connect the past state $\,x(-t)$ of the system with the future state $\,x(t)$ of it by formula $\,x(-t)=F(t,x(t).$. The concept of reflecting function is entered by Vladimir Ivanovich Mironenko.

Definition

For the differential system ${\dot {x}}=X(t,x)$ with the general solution $\varphi (t;t_{0},x)$ in the Cauchy form Reflecting Function is defined by formula $F(t,x)=\varphi (-t;t,x).$

Application

If vector-function $\,x(-t)$ is $\,2\omega$-heriodic with respect to $\,t$, then $F(-\omega ,x)$ is in period $\,[-\omega ;\omega ]$ transformation (Poincaré map) of the differential system ${\dot {x}}=X(t,x)$. Therefore the knowlege of the Reflecting Function give us the opportunity to find out the initial date $\,(\omega ,x_{0})$ of periodic solutions of the differential system and investigate the stability of that solutions.

For the Reflecting Function $\,F(t,x)$ of the system ${\dot {x}}=X(t,x)$ the basic relation

$\,F_{t}+F_{x}X+X(-t,F)=0,$ $\,F(0,x)=x.$

is holding.

Therefore we have an opportunity sometimes to find Poincaré map of the non-integrable in quadrature systems even in elementary functions.

Literature

• Мироненко В. И. Отражающая функция и периодические решения дифференциальных уравнений. — Минск, Университетское, 1986. — 76 с.
• Мироненко В. И. Отражающая функция и исследование многомерных дифференциальных систем. — Гомель: Мин. образов. РБ, ГГУ им. Ф. Скорины, 2004. — 196 с.

Links

• The Reflecting Function Site
• How to construct equivalent differential systems