CDS 140a Winter 2013 Homework 5

From MurrayWiki
Revision as of 04:43, 3 February 2013 by Macmardg (Talk | contribs)

Jump to: navigation, search
WARNING: This homework set is still being written. Do not start working on these problems until this banner is removed.

R. Murray, D. MacMartin Issued: 5 Feb 2013 (Tue)
ACM 101/AM 125b/CDS 140a, Winter 2013 Due: 12 Feb 2013 (Tue)

Note: In the upper left hand corner of the second page of your homework set, please put the number of hours that you spent on this homework set (including reading).

  1. Perko, Section 2.9, problem 3 Use the Lyapunov function $V(x)=x_1^2+x_2^2+x_3^2$ to show that the origin is an asymptotically stable equilibrium point of the system

    \dot{x}=\begin{bmatrix}-x_2-x_1x_2^2+x_3^2-x_1^3\\ x_1+x_3^2-x_2^2\\ -x_1x_3-x_3x_1^2-x_2x_3^2-x_3^5\end{bmatrix}


    Show that the trajectories of the linearized system $\dot{x}=Df(0)x$ for this problem lie on circles in planes parallel to the $x_1,\,x_2$ plane; hence, the origin is stable, but not asymptotically stable for the linearized system.

  2. Perko, Section 2.12, problem 2 Use Theorem 1 [Centre Manifold Theorem] to determine the qualitative behaviour near the non-hyperbolic critical point at the origin for the system

    \aligned \dot{x}&=y\\ \dot{y}&=-y+\alpha x^2+xy \endaligned


    for $\alpha\neq 0$ and for $\alpha=0$; i.e., follow the procedure in Example 1 after diagonalizing the system as in Example 3.