Editing Lyapunov exponent (section)

==Definition of the maximal Lyapunov exponent==
The maximal Lyapunov exponent can be defined as follows:
<math display="block"> \lambda = \lim_{t \to \infty} \lim_{|\boldsymbol{\delta}_0| \to 0}
\frac{1}{t} \ln\frac{| \boldsymbol{\delta}(t)|}{|\boldsymbol{\delta}_0|}</math>

The limit <math>|\boldsymbol{\delta}_0| \to 0</math> ensures the validity of the linear approximation
at any time.<ref name=cencini>{{Cite book |first=M. |last=Cencini|title=Chaos From Simple models to complex systems |editor=World Scientific|year=2010 | publisher=World Scientific |isbn=978-981-4277-65-5  |display-authors=etal}}</ref>

For discrete time system (maps or fixed point iterations) <math> x_{n+1} = f(x_n) </math>, for an orbit starting with <math>x_0</math> this translates into:
<math display="block">\lambda (x_0) = \lim_{n \to \infty}  \frac{1}{n} \sum_{i=0}^{n-1}  \ln | f'(x_i)| </math>