Calculators and numerical differentiation
https://www.hpmuseum.org/forum/thread-15814.html04.11.2020 · Returns the numerical derivative calculated using auto differentiation methods. Note: The nDerivative() algorithm has a limitiation [sic]: it works recursively through the unsimplified expression, computing the numeric value of the first derivative (and second, if applicable) and the evaluation of each subexpression, which may lead to an unexpected result.