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NBCF: Lyapunov Exponent ( Here is the Matlab File)

Last reviewed: July 1, 2012
Tech Article ID: 000

The information in this article applies to:

Finding the largest Lyapunov exponent.

Summary:
The largest Lyapunov exponent is computed using Wolf’s algorithm.

Data Set up:
Data should be a single column file with all numbers, no titles or words.
The data filenames must be *.dat (i.e. s1c1t1.dat or standing.dat).  

Set up:
Click on Matlab on the desk top.
Once you have opened Matlab load the program called LyE_Wolf.m into Matlab.  This can be done by selecting open under File and selecting the appropriate location.
In order to compute the largest Lyapunov exponent, need to specify certain parameters at the top of the program for any calculation
DT = 1/(sampling frequency)
n = number of time steps (n = 3 for 60 Hz is adequate for gait)
dim = embedding dimension
tau = time lag
Run the program by hitting F5.
The following window will pop up.  Select the folder where your data is stored.

Matlab will compute the largest Lyapunov Exponent for all .dat files in the folder, return the value on the current command window (LyE), and save Excel file with results.