Bifurcation diagram
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In
mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
, particularly in
dynamical systems In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in a ...
, a bifurcation diagram shows the values visited or approached asymptotically (fixed points, periodic orbits, or
chaotic Chaotic was originally a Danish trading card game. It expanded to an online game in America which then became a television program based on the game. The program was able to be seen on 4Kids TV (Fox affiliates, nationwide), Jetix, The CW4Kid ...
attractors) of a system as a function of a bifurcation parameter in the system. It is usual to represent stable values with a solid line and unstable values with a dotted line, although often the unstable points are omitted. Bifurcation diagrams enable the visualization of bifurcation theory.


Logistic map

An example is the bifurcation diagram of the
logistic map The logistic map is a polynomial mapping (equivalently, recurrence relation) of degree 2, often referred to as an archetypal example of how complex, chaotic behaviour can arise from very simple non-linear dynamical equations. The map was popula ...
: : x_=rx_n(1-x_n). \, The bifurcation parameter ''r'' is shown on the horizontal axis of the plot and the vertical axis shows the set of values of the
logistic function A logistic function or logistic curve is a common S-shaped curve (sigmoid curve) with equation f(x) = \frac, where For values of x in the domain of real numbers from -\infty to +\infty, the S-curve shown on the right is obtained, with the ...
visited asymptotically from almost all initial conditions. The bifurcation diagram shows the forking of the periods of stable orbits from 1 to 2 to 4 to 8 etc. Each of these bifurcation points is a period-doubling bifurcation. The ratio of the lengths of successive intervals between values of ''r'' for which bifurcation occurs converges to the
first Feigenbaum constant In mathematics, specifically bifurcation theory, the Feigenbaum constants are two mathematical constants which both express ratios in a bifurcation diagram for a non-linear map. They are named after the physicist Mitchell J. Feigenbaum. Histo ...
. The diagram also shows period doublings from 3 to 6 to 12 etc., from 5 to 10 to 20 etc., and so forth.


Symmetry breaking in bifurcation sets

In a dynamical system such as : \ddot + f(x;\mu) + \varepsilon g(x) = 0, which is
structurally stable In mathematics, structural stability is a fundamental property of a dynamical system which means that the qualitative behavior of the trajectories is unaffected by small perturbations (to be exact ''C''1-small perturbations). Examples of such ...
when \mu \neq 0 , if a bifurcation diagram is plotted, treating \mu as the bifurcation parameter, but for different values of \varepsilon , the case \varepsilon = 0 is the symmetric pitchfork bifurcation. When \varepsilon \neq 0 , we say we have a pitchfork with ''broken symmetry.'' This is illustrated in the animation on the right.


See also

*
Bifurcation memory Bifurcation memory is a generalized name for some specific features of the behaviour of the dynamical system near the bifurcation. General information The phenomenon is known also under the names of "''stability loss delay for dynamical bifur ...
*
Chaos theory Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to hav ...
* Skeleton of bifurcation diagram *
Feigenbaum constants In mathematics, specifically bifurcation theory, the Feigenbaum constants are two mathematical constants which both express ratios in a bifurcation diagram for a non-linear map. They are named after the physicist Mitchell J. Feigenbaum. Histo ...


References

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External links


The Logistic Map and Chaos
Chaos theory Bifurcation theory de:Bifurkationsdiagramm {{chaos-stub