Ostrowski numeration
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In mathematics, Ostrowski numeration, named after
non-integer representation of real numbers
.
Fix a positive irrational number α with continued fraction expansion [a0; a1, a2, ...]. Let (qn) be the sequence of denominators of the convergents pn/qn to α: so qn = anqn−1 + qn−2. Let αn denote Tn(α) where T is the Gauss map T(x) = {1/x}, and write βn = (−1)n+1 α0 α1 ... αn: we have βn = anβn−1 + βn−2.
Real number representations
Every positive real x can be written as
where the integer coefficients 0 ≤ bn ≤ an and if bn = an then bn−1 = 0.
Integer representations
Every positive integer N can be written uniquely as
where the integer coefficients 0 ≤ bn ≤ an and if bn = an then bn−1 = 0.
If α is the
Fibonacci representation
of positive integers as a sum of distinct non-consecutive Fibonacci numbers.
See also
References
- Allouche, Jean-Paul; Zbl 1086.11015..
- Epifanio, C.; Frougny, C.; Gabriele, A.; Mignosi, F.; Zbl 1237.68134.
- JFM 48.0197.04.
- Pytheas Fogg, N. (2002). Zbl 1014.11015.