How to check chaotic system using Lyapunov

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Discussion Overview

The discussion centers around the use of Lyapunov exponents to determine whether a system, specifically the Rössler system, exhibits chaotic behavior. Participants seek clarification on the dependence of chaos on parameters and initial conditions, as well as practical methods for calculation.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant asks how to determine if the Rössler system is chaotic, questioning the role of parameters and initial conditions.
  • Another participant requests the title and publication details of the referenced paper to provide more tailored assistance.
  • A later reply suggests that chaos can be determined by numerically solving the differential equations and calculating Lyapunov exponents, stating that a positive Lyapunov exponent indicates chaotic behavior for the given parameters and initial conditions.
  • The same reply references a practical guide for calculating Lyapunov exponents and mentions a specific resource used in the past, though it is noted to be somewhat dated.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the relationship between chaos and system parameters, with some seeking clarification while others provide technical insights. No consensus is reached on the specifics of the calculations or the implications of the parameters.

Contextual Notes

The discussion does not resolve the uncertainties regarding the dependence of chaotic behavior on specific parameters or initial conditions, nor does it clarify the mathematical steps involved in calculating Lyapunov exponents.

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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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.
 
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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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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