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Lyapunov in README

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Ian Jauslin 2025-01-31 11:08:20 -05:00
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README.md
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@ -45,6 +45,11 @@ The available commands are
In addition, if alpha has a negative value (even in between `print_freq`
intervals), a line is printed with the information.
* `lyapunov`: to compute the Lyapunov exponents. This command prints
```time instantaneous_lyapunov lyapunov```
where `instantaneous_lyapunov` is computed from the tangent flow only between
the given time and the previous one.
* `uk`: to compute the Fourier transform of the solution.
* `quiet`: does not print anything, useful for debugging.
@ -138,13 +143,27 @@ should be a `;` sperated list of `key=value` pairs. The possible keys are
* `print_alpha` (0 or 1, default 0): if this is set to 1, then whenever alpha
is negative, its value is printed as a comment.
* `lyapunov_reset` (double, default: `print_freq`): if this is set, then, when
computing the Lyapnuov exponents, the tangent flow will renormalize itself at
times proportional to `lyapunov_reset`. This option is incompatible with
`lyapunov_maxu`.
* `lyapunov_maxu` (double, default: unset): if this is set, then, when
computing the Lyapnuov exponents, the tangent flow will renormalize itself
whenever the norm of the tangent flow exceeds `lyapunov_maxu`. This option
is incompatible with `lyapunov_reset`.
* `algorithm_lyapunov`: the algorithm used to integrate the tangent flow. Can
be `RK4` for Runge-Kutta 4 (default) or `RK2` for Runge-Kutta 2. Adaptive
step algorithms cannot be used for the tangent flow.
# Interrupting and resuming the computation
The computation can be interrupted by sending Nstrophy the `SIGINT` signal
(e.g. by pressing `Ctrl-C`.) When Nstrophy receives the `SIGINT` signal, it
finishes its current step and writes the value of uk, either to `savefile` if
such a file was specified on the command line (using the `-s` flag), or to
The `enstrophy` computation can be interrupted by sending Nstrophy the `SIGINT`
signal (e.g. by pressing `Ctrl-C`.) When Nstrophy receives the `SIGINT` signal,
it finishes its current step and writes the value of uk, either to `savefile`
if such a file was specified on the command line (using the `-s` flag), or to
`stderr`. In addition, when a `savefile` is specified it writes the command
that needs to be used to resume the computation (which essentially just sets
the appropriate `starting_time` and `init:file:<savefile>` parameters. The data