2.3.1. Time Domain (TD)
In the time domain, the statistical parameters used to determine the corresponding RR intervals at any point in time [The triangular index (RRTri) was calculated from a density histogram of the normal RR intervals. The RRtri index was calculated from the density histogram of the normal RR intervals, obtained by dividing the integral of the histogram by the maximum density distribution, i.e., the modal frequency of RR intervals [The triangular interpolation of RR intervals (TINN) is the baseline width of the distribution measured as the base of a triangle, approximating the distribution of all RR intervals, in which the least squares difference was used to determine the triangle [