Talk:Andronov-Hopf bifurcation

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In section "Two-dimensional Case" the sytem of ODEs would imply that \dot{x}_1 = \dot{x}_2 for an initial value x_1(0) = x_2(0). Shouldn't this be two different functions?


Yu.A.: Of course, x_1(0) = x_2(0)=a does not imply \dot{x}_1 = \dot{x}_2, since

\dot{x}_1=\beta a - a + \sigma a(a^2+a^2)=(\beta-1)a+2\sigma a^3

but

\dot{x}_2= a + \beta a + \sigma a(a^2+a^2)=(\beta+1)a+2\sigma a^3


So, function f isn't unique? It is used for both equations in the ODE system.

Yu.A. The "function f" assigns to each (x_1,x_2) two numbers (f_1(x_1,x_2),f_2(x_1,x_2)). Please, read some basic ODE textbook.

So this isn't unique. I already read ODE books but I am used to identifying indexes etc.. I am sorry for misunderstanding. This article is altogether more than excellent. But I have to admit that in my eyes the dimensionality of "the" function f is not correct. As you wrote there is a tuple (f_1(x_1,x_2),f_2(x_1,x_2)) which components should be used in these two equations instead of f.

Yu.A. Both. f is one vector-function of the vector-argument.

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