
68 Practical Biomedical Signal Analysis Using MATLAB
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FIGURE 2.22: Phase portraits of human ECG in three-dimensional space. A two-
dimensional projection is displayed for two values of the delay τ: (a) 12 ms and (b)
1200 ms. (c) represents the phase portrait constructed from ECG of simultaneously
recorded signals from three ECG leads. From [Babloyantz and Destexhe, 1988].
system is predictable before chaotic behavior sets in. The Lyapunov exponent or Lya-
punov characteristic exponent of a dynamical system is a quantity that characterizes
the rate of separation of infinitesimally close trajectories. Quantitatively, the separa-
tion of two trajector ...