Hopf bifurcation
A Hopf bifurcation or Hopf - Andronov bifurcation is a type of local bifurcation in nonlinear systems. It is named after the German - American mathematician Eberhard Frederich Ferdinand Hopf.
Hopf bifurcations are characterized in that when the variation of a parameter, an equilibrium will lose its stability and merges into a limit cycle. Depending on whether this limit cycle is stable or unstable, it is called a supercritical or subcritical Hopf bifurcation.
In a Hopf bifurcation crosses at an equilibrium point ( fixed point ) of the system is a pair of conjugate complex eigenvalues resulting from the linearization of the system Jacobian matrix of the imaginary axis of the complex plane, the bifurcation point, the conjugated eigenvalues are therefore purely imaginary.
The codimension of the Hopf bifurcation is the same as in the Saddle -node bifurcation, the pitchfork bifurcation and the Trans- critical bifurcation equal to one, the other types of bifurcations of codimension 1, are characterized by an eigenvalue of the Jacobian matrix at the fixed point.