How to check chaotic system using Lyapunov

In summary, the conversation discussed the use of Lyapunov to determine if a system is chaotic. The equation for Rossler System (Eq. 1) was mentioned and it was asked if chaotic behavior depends on parameters or initial constants. The speaker also mentioned a research paper that discusses the chaotic behavior of Rossler System with specific initial constants. In response, it was suggested to solve the differential equations numerically and calculate the Lyapunov exponents to determine if the system is chaotic. Additional resources were also provided for further guidance.
  • #1
ohaited
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Greetings!

Hey, can anyone help me? I need an explanation how can Lyapunov help me to check the system weather it is chaotic or not. Let say I have this equation Rossler System Eq.(1)

upload_2018-12-15_20-13-22.png


So how can you tell that the system have chaotic behavior or not? Does it depends on parameters? or from initial constant (a,b,c)? A general and specific clarification is needed. Because I have this paper research that talk about Rossler System Eq. (1) can have chaotic behavior when the initial a=b=0.2 and c= 5.7

Thanks, your consideration is appreciated!
 

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  • #2
Could you please tell us the title of the paper and where/when it was published? It might help a lot to give you the best answer.
 
  • #3
jim mcnamara said:
Could you please tell us the title of the paper and where/when it was published? It might help a lot to give you the best answer.
Hey there, sorry for not attaching the paper with my question. So here it is: Paper
 
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  • #4
ohaited said:
So how can you tell that the system have chaotic behavior or not? Does it depends on parameters? or from initial constant (a,b,c)?

In short you can determine if a particular system is chaotic by solving the differential equations numerically and calculate the Lyapunov exponents along the (non-transient) trajectory. If there is at least one positive Lyapunov exponent then the trajectory is chaotic and hence the system for its given parameters and initial state is considered chaotic.

For a practical guide on how to calculate it you may be inspired by the description on http://sprott.physics.wisc.edu/chaos/lyapexp.htm. Way back at university I used Practical Numerical Algorithms for Chaotic Systems by Parker and Chua, but that is a bit old now (but most likely still relevant).
 
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1. What is a chaotic system?

A chaotic system is a mathematical model that exhibits sensitive dependence on initial conditions, meaning that small changes in the initial conditions can lead to drastically different outcomes.

2. How is the Lyapunov method used to check chaotic systems?

The Lyapunov method is used to analyze the stability of a dynamical system by studying the behavior of its Lyapunov exponents. These exponents measure the rate of divergence or convergence of nearby trajectories in phase space, providing insight into the system's chaotic behavior.

3. Can the Lyapunov method be applied to any chaotic system?

Yes, the Lyapunov method can be applied to any system that can be described by a set of differential equations, regardless of its complexity or dimensionality.

4. How do you calculate the Lyapunov exponents?

The Lyapunov exponents can be calculated using various numerical methods, such as the Gram-Schmidt procedure or the Benettin algorithm. These methods involve iteratively computing the tangent vectors and their norms along a trajectory and then averaging the results over time.

5. What are the practical applications of using the Lyapunov method to check chaotic systems?

The Lyapunov method has various practical applications in fields such as physics, biology, economics, and engineering. It can help predict the long-term behavior of a system, identify unstable regions, and design control strategies to stabilize chaotic systems.

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