variable period

Fourier series of periodic functions with variable period and evaluation of the variable period for determination of heart rhythm variability

The article draws attention to the fact that in addition to periodic empirical signals, whose model is a periodic function, there are signals that behave like periodic, but the period of their values repetition is no longer constant and changes in some way. An illustrative example is electrocardiograms (ECGs) obtained during or after an impact of some “exciter of calm”, for example, physical exertion, on the patient. How to study periodic signals with a variable period (PSVP)?

Analytical approaches for definition of functions with variable period and information technology for determining of Fourier coefficients

Main achievements of function theory with variable period have been described. The tasks aimed at their further study, namely the task of functions with variable period “approximation” Fourier series, and development the appropriate information technologies of their analysis have been emphasized. To make the investigation of the methods of function study with variable period testing possible different ways of analytical definition of such functions have been developed.