Continued Fraction Gauss Map

Iterate T(x) = {1/x} — invariant measure dμ = dx/((1+x)ln2), convergents, and CF expansion

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CF expansion [a₀; a₁, a₂, …]
Best rational approx (p/q)
Gauss map: T(x) = {1/x} = 1/x − ⌊1/x⌋
The floor ⌊1/x⌋ gives the next CF coefficient aₙ.

Invariant measure: μ(A) = ∫_A dx/((1+x)ln2) — the Gauss–Kuzmin–Wirsing distribution.

φ has CF [1;1,1,1,…] — the "most irrational" number; worst rational approximation.