Long term measurement of heart rate furnishes important information of cardiac anomalies. During a period of about 24 hours pulse rate of a patient at the University Hospital Aachen has been measured. Thus, we have a lots of pulse values, which are important for a medical doctor treating sick patients. We use Maple to analyze this data. At first the given data have been interpolated by cubic spline functions. Then, these functions have been approximated by nonlinear regression and also by Fourier series.