Determining Stability of Equilibrium Point for x'=y-x3-xy2, y'=-x-x2y-y3

In summary, the given system has state variables x1 and x2, and the equilibrium point is found to be at (0,0). To determine stability, we can use a Lyapunov function V(x) = (x1^2 + x2^2)/2, which leads to the conclusion that the system is stable.
  • #1
onie mti
51
0
i have this system

x'=y-x3-xy2
y'=-x-x2y-y3

i worked it out and found the equilibrium point to be 0.

how do i determine whether it is stable, assymp stable or not stable
 
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  • #2
onie mti said:
i have this system

x'=y-x3-xy2
y'=-x-x2y-y3

i worked it out and found the equilibrium point to be 0.

how do i determine whether it is stable, assymp stable or not stable

Let's define $x_{1}$ and $x_{2}$ the state variables, so that the system becomes...

$\displaystyle x_{1}^{\ '} = x_{2} - x_{1}^{3} - x_{1}\ x_{2}^{2}$

$\displaystyle x_{2}^{\ '} = - x_{1} - x_{1}^{2}\ x_{2} - x_{2}^{3}\ (1)$

You can choose as Lyapunov function $\displaystyle V(\overrightarrow x)= \frac{x_{1}^{2} + x_{2}^{2}}{2}$, so that is...

$\displaystyle V^{\ '} (\overrightarrow x) = x_{1}\ x_{2} - x_{1}^{4} - x_{1}^{2}\ x_{2}^{2} - x_{1}\ x_{2} - x_{1}^{2}\ x_{2}^{2} - x_{2}^{4} = - (x_{1}^{2} + x_{2}^{2})^{2} \le 0\ \forall \overrightarrow x\ (2)$

... so that the system is stable...

Kind regards

$\chi$ $\sigma$
 

FAQ: Determining Stability of Equilibrium Point for x'=y-x3-xy2, y'=-x-x2y-y3

1. How do you determine the equilibrium point for this system of equations?

To determine the equilibrium point of a system of equations, we need to set both equations equal to zero and solve for the values of x and y that satisfy both equations simultaneously. This will give us the x and y coordinates of the equilibrium point.

2. What does stability mean in the context of this system of equations?

In this system of equations, stability refers to the behavior of the system at the equilibrium point. A stable equilibrium point means that the system will return to the equilibrium point after being perturbed, while an unstable equilibrium point means that the system will move away from the equilibrium point after being perturbed.

3. How do you determine the stability of the equilibrium point?

To determine the stability of the equilibrium point, we need to analyze the behavior of the system near the equilibrium point. This can be done by linearizing the system around the equilibrium point and examining the eigenvalues of the resulting Jacobian matrix. If the eigenvalues have negative real parts, the equilibrium point is stable. If the eigenvalues have positive real parts, the equilibrium point is unstable.

4. Can this system have multiple equilibrium points?

Yes, this system can have multiple equilibrium points. The number of equilibrium points depends on the specific values of the parameters in the equations. For example, if the parameters are such that the equations have multiple solutions when set equal to zero, then there will be multiple equilibrium points.

5. What factors can affect the stability of the equilibrium point?

The stability of the equilibrium point can be affected by factors such as the values of the parameters in the equations, the initial conditions of the system, and the behavior of the system near the equilibrium point. Additionally, the type of equilibrium point (stable or unstable) can also be affected by the specific form of the equations and the values of the parameters.

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