At a meeting of the Bohemian philosophical society in December 1921 Dr. Jasek reported the discovery among the papers of Bernhard Bolzano of a manuscript in which is described the construction of a continuous non-differentiable function. This function was devised more than thirty years before Weierstrass constructed his now well-known function. But while Weierstrass proved that his function possessed a derivative at no point, Bolzano showed the non-differentiability of his function only at a countable set of points everywhere dense. It is possible however to prove that the Bolzano function possesses a derivative at no point of the interval.
Proceedings of the Iowa Academy of Science
©1940 Iowa Academy of Science, Inc.
Daniells, Marian E.
"A Note on a Bolzano Function,"
Proceedings of the Iowa Academy of Science, 47(1), 273-276.
Available at: https://scholarworks.uni.edu/pias/vol47/iss1/67