diff --git a/300s School/ME 2016 - Nonlinear Dynamical Systems 1/2024-10-28 Stability.md b/300s School/ME 2016 - Nonlinear Dynamical Systems 1/2024-10-28 Stability.md index 03d9f414f..3bb46570b 100644 --- a/300s School/ME 2016 - Nonlinear Dynamical Systems 1/2024-10-28 Stability.md +++ b/300s School/ME 2016 - Nonlinear Dynamical Systems 1/2024-10-28 Stability.md @@ -22,5 +22,22 @@ $$\text{dist}[x, c] = \min_{y \in C}|x-y|$$ Where c is a curve. Where in the plane we're using the minimum of the 2 norm. +## Summary Stable half-paths can be generally stable, approaching an equilibrium, or periodic. -Unstable half-paths exceed the bound $\epsilon$ somewhere. \ No newline at end of file +Unstable half-paths exceed the bound $\epsilon$ somewhere. + +Poincare cannot handle the time dependency of systems. As a result, we can't really use Poincare to handle real systems. That leads us to..... + +# Lyapunov Stability +Basically extend the 2D distance formula we talked about last time to include n dimensions. (May need to analyze complex solutions as well). + +Let's define Lyapunov Stability: +>[!note] Lyapunov Stability Definition +>Let $x^*$ be a real or complex solution of $x = X(x,t)$. Then, +>1. $x^*$ is lyapunov stable iff for each value of $\epsilon>0$ however small there is a corresponding value of $\delta>0$ such that +>![[Pasted image 20241028152704.png]] +>2. If the system is autonomous, then we can disregard the idea of $t_0$ in 1. +>3. Otherwise, we call the system unstable in the sense of Lyapunov. + +This stability definition defines that for an autonomous system, Lyapunov stability is sufficient for Poincare stability. + diff --git a/Pasted image 20241028152704.png b/Pasted image 20241028152704.png new file mode 100644 index 000000000..ef616b135 Binary files /dev/null and b/Pasted image 20241028152704.png differ