Heart rate variability (HRV) is an indicator of autonomic activity. As such, it is said to be able to detect signs of disease and can be used to estimate disease status. Recently, the usefulness of the QT interval has been discussed. The reason for this is that QT interval variability is said to be a risk marker for arrhythmia and cardiovascular death. However, this is only a possibility, and whether it actually functions as a risk marker has not yet been established. All S, Q, R, T and P peaks from electrocardiograms (ECGs) were obtained with several Matlab algorithms and compared, and then RR and QT intervals were calculated. On the other hand, it is generally known that there are clear differences in QT interval and RR interval between men and women and with age. Therefore, this project codified an algorithm for HRV analysis implemented in Matlab to see if there are similar differences in QT, RR interval indicators between men and women and by age. For this purpose, several indicators were implemented in Matlab and applied to the QT and RR intervals based on linear and nonlinear algorithms.