Eigenvalues for Equilibrium Points of First Order Nonlinear DE

In summary, the conversation discusses finding equilibrium points and eigenvalues for the given equation and determining their stability. The equilibrium points are found by setting dy/dx = 0 and the derivative at each point is evaluated to determine stability. The derivative at each equilibrium point can also be considered as the eigenvalues for this equation. In a system of equations, the eigenvalues would need to be found by setting up a matrix and solving for its eigenvalues.
  • #1
jsi
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Homework Statement



dy/dx = y^3-3y^2+2y
it's asking for equilibrium points and for the eigenvalues and stability at each point.

Homework Equations





The Attempt at a Solution



I found the equilibrium points by setting dy/dx = 0 as we were taught to do in class and got y = 0, 1, 2. Then I took the derivative of the equation and evaluated it at each point to determine stability and found derivative at 0 = 2, at 1 = -1, and at 2 = 2 so the first and third are unstable and the second is stable. I'm confused on how to find eigenvalues for just one equation because I'm used to doing it for 2 equations. Have I already done it by evaluating the equilibrium points at the derivative and those are the eigenvalues or is there more to it? Thanks!
 
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  • #2



Great job on finding the equilibrium points and determining their stability! You are correct that the derivative at each equilibrium point can be considered as the eigenvalues for this equation. This is because the eigenvalues represent the rates of change at each equilibrium point, and in this case, the derivative at each point represents the rate of change of the function itself. So, you have already found the eigenvalues for this equation. However, if you were dealing with a system of equations, you would need to find the eigenvalues by setting up a matrix and solving for its eigenvalues. Keep up the good work!
 

Related to Eigenvalues for Equilibrium Points of First Order Nonlinear DE

1. What are eigenvalues for equilibrium points?

Eigenvalues for equilibrium points are the values that determine the stability or instability of a system at a given equilibrium point. They are obtained by linearizing the nonlinear differential equation at the equilibrium point.

2. How do eigenvalues affect the behavior of a system?

Eigenvalues can determine whether a system is stable, unstable, or neutral at an equilibrium point. A system with all negative eigenvalues at an equilibrium point is stable, while a system with at least one positive eigenvalue is unstable. A system with at least one zero eigenvalue is neutral.

3. How are eigenvalues calculated for a nonlinear differential equation?

Eigenvalues are calculated by linearizing the nonlinear differential equation at an equilibrium point and finding the solutions to the resulting linear system of equations. This can be done through methods such as the Jacobian matrix or the characteristic polynomial.

4. Why are eigenvalues important in the study of nonlinear differential equations?

Eigenvalues allow us to analyze the stability and behavior of a nonlinear system at equilibrium points. They provide valuable information about the long-term behavior of a system and can help predict and control the behavior of complex systems.

5. Can eigenvalues change over time in a nonlinear system?

Yes, eigenvalues can change over time in a nonlinear system. As the system evolves and moves away from an equilibrium point, the eigenvalues will also change. This is why it is important to analyze the eigenvalues at each equilibrium point to understand the behavior of a system over time.

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