Minkowski's Question-Mark Function

Minkowski's question-mark function, denoted ?(x), maps the rational numbers to the dyadic rationals and irrational quadratic numbers to non-dyadic irrationals, built from the continued-fraction expansion of its argument. It is a continuous, strictly increasing, singular function, meaning its derivative is zero almost everywhere even though the function itself increases across its whole domain. The function provides a bridge between the Stern-Brocot tree's ordering of the rational numbers by continued fractions and the ordinary binary ordering of the real numbers on the unit interval. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/