Logistic Map and cobweb diagrams

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SUMMARY

The discussion focuses on the logistic map defined by the equation xn+1 = 2xn(1 - xn) and its implications in studying discrete dynamical systems. Participants explore the stability of fixed points and the convergence of numerical solutions to these points. The method involves plotting the function g(x) = 2x(1 - x) alongside the line y = x to analyze the system's evolution from an initial value, specifically x0 = 0.01, over a defined number of iterations. The project deadline is imminent, prompting a request for guidance on executing these calculations and visualizations.

PREREQUISITES
  • Understanding of discrete dynamical systems
  • Familiarity with logistic maps and fixed points
  • Basic knowledge of numerical methods for convergence analysis
  • Proficiency in plotting functions using software tools like MATLAB or Python
NEXT STEPS
  • Implement the logistic map in MATLAB or Python to compute iterations
  • Learn how to plot functions and visualize convergence using libraries like Matplotlib
  • Study the concept of stability in fixed points within dynamical systems
  • Read "Chaos" by Peitgen, focusing on the chapter about Deterministic Chaos and its relation to the logistic map
USEFUL FOR

Students and researchers in mathematics, particularly those studying chaos theory and dynamical systems, as well as anyone interested in numerical methods for analyzing stability in mathematical models.

S.Parker
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Hi all. I am new here and I am having difficulty figuring out what exactly is required of me in this question. If someone could be so kind as to explain. For this part of the project we will consider the evolution of a discrete dynamical system given by a logistic map.
We will consider a logistic map given by

xn+1 = 2xn(1- xn) (1)

on the interval x 2 [0; 1]. A fixed point of this equation is obtained when xn+1 = xn, i.e. when

x = 2x(1 - x):

If we let

g(x) = 2x(1 - x)

then a fixed point is obtained when

x = g(x):

In our case, we can solve for this analytically, but we will investigate how a numerical solution will converge on
the solution. What we want to know is
Does the system evolve to a stable solution? i.e. is the fixed point stable?
If so, what value of x does the system evolve to?
To see how this works, essentially we will find the intersection of the straight line y = x with the function
g(x). Start by plotting y = x and g(x) on the same se of axes. Now let us start with an initial value of x and
see how the system evolves from there. Choose a suitable value of N for the number of iterations. Choose
2
x0 = 0:01, and then calculate each new value of xn from this starting value, using (1). Do this by creating a vector
x = [x0; x1; x2; : : : xN]. Plot a graph of x vs step number n. This will show you how x evolves with each new

Homework Equations

The Attempt at a Solution


To be honest, I have not tried it yet, as I am not sure of what to do exactly. I know this part is required, but I really do need the help (project due this Friday)
 
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S.Parker said:
I am not sure of what to do exactly. I know this part is required, but I really do need the help (project due this Friday)

I believe the best approach is for you to find "Chaos" by Peitigen and go directly to the chapter on Deterministic Chaos. Never heard it called cob webs but you'll see what they're doing with the logistic map which I guess looks like webs.
 

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