\"Uber die Funktionen des Irrationalit\"atsma\ss es

Abstract

We study two irrationality measure functions $\psi_\alpha^{[2]} (t) $ and $\psi_\alpha^{[2]*} (t)$ related to the "second best" approximations to a real numbers and prove some results on the structure of the corresponding Diophantine spectra. It happened that the first two elements of the spectrum for the function $\psi_\alpha^{[2]*} (t)$ are associated with the numbers $\frac{1+\sqrt{5}}{2}$ and $e =\sum_{n=0}^\infty \frac{1}{n!}$.