Beygelzimer E, Beygelzimer Y. A simple way to estimate the derivative of an empirical function by its values at unequally spaced points. Materials working by pressure [Internet]. 2022 Dec. 14 [cited 2025 Dec. 5];(1(51):21-9. Available from: http://omd.dgma.donetsk.ua/index.php/main/article/view/185