To compute the Lyapunov exponents we followed this procedure. From the output of swift_lyap2 we read the data in lyap2.out (time and distances) and construct a serie of the form:
t - ln(d(t)/d(0))
0.0 0.0
1.0 ln(d(1)/d(0))
2.0 ln(d(2)/d(0))
....
Then we perform a linear least-square fit on the
curve [t,ln(d(t)/d(0))]. Since d(t) ~ d(0)*exp(L*t) =>
ln(d/d0) ~ L*t , the slope should be equal to L. If your data set
is about 10*(1/L) long, this should give a quite
accurate computation. If your data points reach numbers
as high as 10^300 and overflow, it is certain that you will have a quite
good estimate with the first part of the series (from an email of
Kleomenis Tsiganis).
Here we the results of this procedure for the low-resolution survey. We report a contour plot of the log10 of Lyapunov times, without the median filtering.
In the following figures we report a) Lyapunov times (log10)
after the use of the median filter, b) Lyapunov exponents, and c) the results
of the Frequency analysis method for the same survey.
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In the following plots we report the results of simulations
that used analytical solutions from the Bretagnon model. On the left
there are the values of Lyapunov times, and on the right the analytical
solution used for
Saturn. Note that when only secular terms
are considered Lyapunov times are much longer, and we do not see the feature
with larger lyapunov times associated with the most chaotic region found
with the FAM.
This seems to suggest that this feature might be associated
with the great-inequality terms.
SEC
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A2-1GISEC
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