Finding the eigenvectors (and behavior of solution) around the

Somefantastik
Messages
226
Reaction score
0
finding the eigenvectors (and behavior of solution) around the critical points found in this thread: https://www.physicsforums.com/showthread.php?t=258349&referrerid=110346

D_{f} = \[\begin{pmatrix}32x & 18y \\ 32x & -32y\end{pmatrix}\]

D_{f}(1,1) = \[\begin{pmatrix}32 & 18 \\ 32 & -32\end{pmatrix}\]

= \[\begin{pmatrix}16 & 9 \\ 16 & -16 \end{pmatrix}\]

det(A-\lambda I) =\[\begin{pmatrix} 16-\lambda & 9 \\ 16 & -16- \lambda \end{pmatrix}\]

= -256 + \lambda^{2} - 146 \ => \ \lambda = ^{+}_{-}20

\lambda_{1} = 20:

(A-\lambda_{1} I)\xi^{(1)} = 0 \ => \ \[\begin{pmatrix} -4 & 9 \\ 16 & -36 \end{pmatrix}\]\xi^{(1)} = 0

I can't get LaTeX to cooperate with me, that's supposed to say [-4 9; 16 -36]ξ(1) = 0

=> \ \xi^{(1)} = \left[^{9}_{4} \right]

Having trouble finding \xi^{(2)} when \lambda_{2} = -20.

Keeps coming out to be [0 0]T.

Any suggestions?
 
Physics news on Phys.org


Looks like you can't reduce the matrix before you do det(A - tI). Figured it out; thanks for looking.
 
Thread 'Direction Fields and Isoclines'
I sketched the isoclines for $$ m=-1,0,1,2 $$. Since both $$ \frac{dy}{dx} $$ and $$ D_{y} \frac{dy}{dx} $$ are continuous on the square region R defined by $$ -4\leq x \leq 4, -4 \leq y \leq 4 $$ the existence and uniqueness theorem guarantees that if we pick a point in the interior that lies on an isocline there will be a unique differentiable function (solution) passing through that point. I understand that a solution exists but I unsure how to actually sketch it. For example, consider a...
Back
Top