The Quadratic Family in Dynamical Systems


The study of the behavior of systems that change over time is known as dynamical systems theory in mathematics. Mathematical equations can describe these systems, and one of the most well-known families of equations in dynamical systems is the quadratic family.

Definition of the Quadratic Family

The quadratic family is a set of equations that can be written in the form:

xn+1 = axn2 + bxn + c

where xn represents the state of the system at time n, and a, b, and c are constants.

Properties of the Quadratic Family

The quadratic family exhibits several interesting properties that make it a popular subject of study in dynamical systems.

Fixed Points and Stability

One of the key properties of the quadratic family is the existence of fixed points, which are values of xn that do not change over time. These fixed points can be found by setting xn+1 equal to xn and solving for x. Depending on the values of a, b, and c, the fixed points can be stable or unstable.

If the fixed points are stable, it means that if the system starts near one of these points, it will eventually converge to that point. On the other hand, if the fixed points are unstable, the system will move away from them over time.


Another fascinating property of the quadratic family is its ability to undergo bifurcations. A bifurcation occurs when the behavior of the system changes abruptly as a parameter is varied. In the case of the quadratic family, the parameter that is typically varied is the value of a.

As the value of a is changed, the system can transition from having a single stable fixed point to having multiple stable fixed points. This bifurcation can lead to the emergence of complex behavior, such as periodic orbits or chaotic dynamics.

Period Doubling and Chaos

One of the most famous phenomena associated with the quadratic family is period doubling. Period doubling occurs when a stable fixed point undergoes a bifurcation and becomes unstable, leading to the emergence of a stable periodic orbit with twice the period of the original fixed point.

As the value of a is further increased, the system can undergo successive period-doubling bifurcations, leading to the creation of periodic orbits with increasingly more extended periods. Eventually, the system can enter a state of chaos, where the behavior becomes highly unpredictable and sensitive to initial conditions.

Applications of the Quadratic Family

The quadratic family has applications in various fields, including physics, biology, and economics. The behavior of physical systems, viz., the motion of celestial bodies or the kinetics of chemical reactions, can be modeled in physics using the quadratic family.

In biology, the quadratic family can be applied to study population dynamics, predator-prey interactions, and the spread of infectious diseases. In economics, the quadratic family can be used to model economic growth, investment decisions, and market dynamics.


The quadratic family is a fascinating subject in dynamical systems theory. Its properties, such as fixed points, bifurcations, and chaos, make it an affluent area of study with applications in various fields. Researchers can learn more about the dynamics of complex systems and forecast their future behavior by analyzing the behavior of the quadratic family.

You May Also Like

More From Author

+ There are no comments

Add yours