...\heartrate_analysis_python-1.1\heartpy\heartpy.py", line 518, in calc_fd_measures rr_x_new = np.linspace(rr_x[0], rr_x[-1], rr_x[-1]) File "<__array_function__ internals>", line 180, in linspace File "C:\Python310\lib\site-packages\numpy\core\function_base.py", line 120, in linspace num = operator.index(num) TypeError: 'numpy.float64' object cannot be interpreted as an integer