HRnV-Calc: A Software for Heart Rate n-Variability and Heart Rate Variability Analysis. - Chenglin Niu; Dagang Guo; Marcus Eng Hock Ong; Zhixiong Koh; Guerry Alexiane Laure Marie-Alix; Andrew Fu Wah Ho; Zhiping Lin 001; Chengyu Liu 001; Gari D. Clifford; Nan Liu 003 (J. Open Source Softw., 2023)