The theory of derived numbers is developed and the way to use it in the study of nondifferentiable functions behavior is presented.
Alferov, G., Ivanov, G., Sharlay, A., & Fedorov, V. (2019). Application of derived numbers theory in problem of function extremum. In AIP Conference Proceedings (Vol. 2116). American Institute of Physics Inc. https://doi.org/10.1063/1.5114062