Non-linear dynamics approach to a manifold of a saddle point using power series

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Homework Help Overview

The discussion revolves around a problem in non-linear dynamics, specifically related to the analysis of a saddle point and the determination of coefficients for stable and unstable manifolds using power series. The original poster references a problem from Strogatz's book on Non-linear Dynamics and Chaos, focusing on a saddle node located at (1,1) and the curves passing through this point.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to find coefficients a1, a2, and a3 for the power series representation of the manifolds. There is an attempt to substitute known values into the equation, but the original poster expresses a lack of sufficient equations to solve for the coefficients. Questions arise regarding the interpretation of known points related to the unstable manifold.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the meaning of known points associated with the unstable manifold. Some guidance has been offered regarding the nature of these points, but no consensus has been reached on how to proceed with the calculations for the coefficients.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is an emphasis on understanding the qualitative behavior of the system and approximating the function of the manifolds.

iratxo_flores
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Homework Statement


Im taking a dynamics course and I am using The strogatz book Non-linear Dynamics and Chaos
I need to solve a problem that is similar to problem 6.1.14
Basically it consist in the following

You have a saddle node at (Ts,Zs) which is (1,1). Consider curves passing through this saddle point :

Z= Zs +h(T-Ts)

where h(s) is a power series:

h(s)= a1s+a2s2+a3s3+...

Find the coefficients for a1, a2 and a3+ for both stable and unstable manifolds of the saddle node at (Ts,Zs)




Homework Equations



I do know the following about the Unstable manifold (0,2) and (1,1) and (5,0) and for the stable manifold (0,0) and (1,1). all (T,Z) I am supposed to use the equation of above and figure out the coefficients.



The Attempt at a Solution



I already try to substitute the equation with the values that i know of but I am 1 equation short

any ideas?
 
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iratxo_flores said:

Homework Statement


Im taking a dynamics course and I am using The strogatz book Non-linear Dynamics and Chaos
I need to solve a problem that is similar to problem 6.1.14
Basically it consist in the following

You have a saddle node at (Ts,Zs) which is (1,1). Consider curves passing through this saddle point :

Z= Zs +h(T-Ts)

where h(s) is a power series:

h(s)= a1s+a2s2+a3s3+...

Find the coefficients for a1, a2 and a3+ for both stable and unstable manifolds of the saddle node at (Ts,Zs)




Homework Equations



I do know the following about the Unstable manifold (0,2) and (1,1) and (5,0) and for the stable manifold (0,0) and (1,1). all (T,Z) I am supposed to use the equation of above and figure out the coefficients.
I have no idea what you mean by this! For the unstable manifold, you "know" (0, 2), (1, 1), and (5, 0). What do you mean you "know" them? Are they points? vectors?



The Attempt at a Solution



I already try to substitute the equation with the values that i know of but I am 1 equation short

any ideas?
 
HallsofIvy said:
I have no idea what you mean by this! For the unstable manifold, you "know" (0, 2), (1, 1), and (5, 0). What do you mean you "know" them? Are they points? vectors?

they are points

http://img502.imageshack.us/img502/3485/manifold.png

thats a sketch of the overall qualitative behaviour of the system, (0,2) and (5,0) are stable nodes and (0,0) is unstable. Of course i don't know the exact function of the manifolds, but i think i can make an approximation by using Z=Zs+h(T-Ts), which are the curves that pass through the saddle node (1,1)What I am being asked to answer, and don't know how to do.. is to determine the coefficients for both the unstable and stable manifolds,
 
Last edited by a moderator:
any ideas?
 

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