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

iratxo_flores
Messages
3
Reaction score
0

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?
 
Physics news on Phys.org
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?
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

Similar threads

Back
Top