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2.1 Nonlinear measures
EEG signals, which have a structure similar to random and irregular patterns, are recently viewed to be fractals.EEG signals, which have a structure similar to random and irregular patterns, are recently viewed to be fractals. Fractal is a complex shape and Mandelbrot has argued that there is a natural dimension in which each fractal sits most parsimoniously. The fractal Dimension D of a planar curve is D=log (L)/log (d) where L is the length of the curve and d is the diameter of the planar extent. A running fractal dimension can give a rough idea about the changing patterns of brain activity during the entire recording period . Another measure of a complex dynamical system is that of attractor dimension, which refers to the ability of a space to contain a set of points (reconstructed phase space vectors). The attractor dimension or correlation dimension of EEG may be calculated by Singular Value Decomposition (SVD) of small sets of data on the reconstructed attractor .