conatus.expert.amplitude_equation

conatus.expert.amplitude_equation(system, x0, parameter, *, kind, observable, par=None, **nf_kw)

Landau equation for the observable amplitude A = observable(x − x0) (linear functional).

kind: “stationary” (zero eigenvalue; the quadratic coefficient must vanish, e.g. by a declared symmetry, else it is refused: a transcritical point has no cubic Landau law) or “oscillatory” (Hopf). Extra keywords go to normal_form() (symmetry, weight, omega…).

Parameters:

• system (DynamicalSystem)

• x0 (ndarray)

• parameter (str)

• kind (str)

• observable (Callable[[ndarray], complex])

• par (Mapping[str, float] | None)

Return type:

LandauEquation