“…In recent past, many nonlinear methods such as Lyapunov exponents [10,22], correlation dimension (D2) [10,29,30], fractal dimension [31][32][33][34][35], 1/f slope [36], approximate entropy [10], detrended fluctuation analysis (DFA) [37,38], Poincare geometry [39][40][41], recurrence quantification analysis (RQA) [42][43][44][45], higher order spectrum (HOS) [46] are studied for diagnosis of CAD. In [38], it is shown that DFA and fractal dimension features exhibited lower values for CAD compared to normal heart rate signals.…”