A method of calculating the heart rate variability of the human heart to be
used in an ECG monitor comprises the following procedural steps:
scanning of the ECG signal received from the ECG monitor during a scanning
interval,
determining from the scanned ECG signals a number of discrete measuring
values representative of the heart rate variability, and
evaluating these measuring values on the basis of the Fourier
transformation, wherein the frequency spectre of the measuring values is
calculated from the Fourier coefficients of the Fourier transformation,
which are for their turn calculated from a combination of said measuring
values with the sinus- and cosinus-shaped Fourier vectors of the Fourier
transformation wherein the Fourier vectors are involved in the calculation
in the form of a number of discrete real numerical vector values, and
replacing of the numerical vector values for calculating the frequency
spectrumof the scanned measuring values by rough, integral approximate
vector values of a limited number which roughly form the shape of the
Fourier vectors.