Author Topic: Q4 problem 2  (Read 3110 times)

Yuan Bian

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Q4 problem 2
« on: November 12, 2014, 09:03:38 PM »
Q2: 7.6 #6
r2+9=0
r1=3i, r2=-3i
pure imaginary eigenvalue, so it's stable center
also whole soln is in the q1 fisrt post.
« Last Edit: November 12, 2014, 10:25:37 PM by Victor Ivrii »

Guang_Yang

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Re: Q4
« Reply #1 on: November 12, 2014, 09:53:49 PM »
7.6 #6

Tao Hu

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Re: Q4 problem 2
« Reply #2 on: November 13, 2014, 03:36:44 PM »
How to determine the direction of the circular phase portrait? What is the difference between clockwise and anti-clockwise?

Yuan Bian

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Re: Q4 problem 2
« Reply #3 on: November 13, 2014, 09:13:45 PM »
from prof Victor Ivrii : "Why you just don't learn a very simple criteria for the center or focus: if the top-right element of 2Ã—2 matrix is >0 the orientation is clock-wise; otherwise it is counter-clock-wise."
« Last Edit: November 13, 2014, 09:21:54 PM by Yuan Bian »

Shuyang Wang

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Re: Q4 problem 2
« Reply #4 on: November 13, 2014, 09:52:56 PM »
Just a plot by software