Finished Report: PDF

Finished Presentation: PDF

*****IN PROGRESS*****

Normal form of the bifurcation

It is an iterative map $F: \mathbb{R}^{2} \rightarrow \mathbb{R}^{2}$ such that

\[\boldsymbol{x}_{n+1}= F(\boldsymbol{x_n})=\begin{cases}A_{L} \boldsymbol{x}+\boldsymbol{m} & x \leqslant 0 \\ A_{R} \boldsymbol{x_n}+\boldsymbol{m} & x \geqslant 0\end{cases}\]

where

\(A_{\alpha}=\left[\begin{array}{cc}T_{\alpha} & 1 \\ -D_{\alpha} & 0\end{array}\right],\quad (\alpha=L \text{ or } R)\) $L$ and $R$ indicate Left or Right side of the y-axis.

\[\boldsymbol{m}=\left[\begin{array}{l}\mu \\ 0\end{array}\right],(\mu \text{ is a constant}) \quad \boldsymbol{x_k}=\left[\begin{array}{l}x_{k}\\y_{k}\end{array}\right]\]

In matrix notation:

\[\left[\begin{array}{l}x_{n+1} \\ y_{n+1}\end{array}\right]=\left[\begin{array}{cc}T_{\alpha} & 1 \\ -D_{\alpha} & 0\end{array}\right]\left[\begin{array}{l}x_{n} \\ y_{n}\end{array}\right]+\left[\begin{array}{l}\mu \\ 0\end{array}\right]\]

Some preliminary random test with the map $F$

Four parameters $T_{L}, D_{L}, T_{R}, D_{R}$ are randomly chosen from the interval $(-2,2)$.

Let $\mu=1$ without loss of generality.

Start the iteration $F$ from origin \(\left[\begin{array}{l}0 \\ 0\end{array}\right]\)

Number of iterations $n=2000$ or $n=500$

Following pictures are observed.

Some uninteresting pictures where a straight line appears are omitted. For example,

Restrictions on $A_R$

Now if we put restriction on $A_R$, i.e. $T_{R}, D_{R}$, such that under $n$ iterations on the right, the point lands on y-axis:

\[F^n(O)=\left[\begin{array}{l}0 \\ y_n\end{array}\right]\]

It is no doubt that \(\left[\begin{array}{l}0 \\ y_n\end{array}\right]\) will then be mapped to some point on the x-axis: \(\left[\begin{array}{}y_n+\mu \\ 0\end{array}\right]\)

Let $y_n=-2$ in our case.

Still let $\mu=1$.

Following ploygons are generated for different $n$.

For a series of $n$, under the same scale in axes, it is easy to see the behaviour of the ploygons for increasing $n$ with a GIF image: