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(a)
(b)
(c)
(d)
Fig. 4.7. Evolution of cells and clustering coefficients for several types of behaviors: ( a )
Class II with very long transients; ( b ) Class III; ( c ) Class IV; ( d ) Class I (using Wolfram's
taxonomy). Note that the clustering coefficient (plotted on vertical axis in the lower graphs)
converges towards a “steady state” in the sense of a constant variance. This variance is lar-
ger for chaotic dynamics and is considered for the last 20% of the iterations, to detect the
transient phenomena much accurately
element is the absolute value of the corresponding element in the input matrix. For
instance, in the case of one-dimensional arrays with N cells, the above formula be-
comes:
ª
º
N
x
x
2
x
1
i
1
i
1
i
,
(4.4)
C
¦
1
«
»
N
2
i
1
¬
¼
>
@
where
.
X
x
,...
x
,..
x
1
i
N
It is interesting to note that the clustering coefficient defined as above is based
on a diffusive filter applied to the matrix of cell states. It is also related to a quan-
tity, the current entering a multiport-cell in a Reaction-Difussion CNN , essential
for the local activity theory [8].
Before computing the transient length, it is necessary to have the whole time-
sequence ^` T
computed. Let us now consider the following two Matlab
C
t
t
1
,..
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