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On nodal sets and nodal domains on S 2 and 2

Alexandre Eremenko, Dmitry Jakobson, Nikolai Nadirashvili (2007)

Annales de l’institut Fourier

We discuss possible topological configurations of nodal sets, in particular the number of their components, for spherical harmonics on S 2 . We also construct a solution of the equation Δ u = u in 2 that has only two nodal domains. This equation arises in the study of high energy eigenfunctions.

On subsequences of convergents to a quadratic irrational given by some numerical schemes

Benoît Rittaud (2010)

Journal de Théorie des Nombres de Bordeaux

Given a quadratic irrational α , we are interested in how some numerical schemes applied to a convenient function f provide subsequences of convergents to α . We investigate three numerical schemes: secant-like methods and formal generalizations, which lead to linear recurring subsequences; the false position method, which leads to arithmetical subsequences of convergents and gives some interesting series expansions; Newton’s method, for which we complete a result of Edward Burger [1] about the existence...

On substitution invariant Sturmian words: an application of Rauzy fractals

Valérie Berthé, Hiromi Ei, Shunji Ito, Hui Rao (2007)

RAIRO - Theoretical Informatics and Applications

Sturmian words are infinite words that have exactly n+1 factors of length n for every positive integer n. A Sturmian word sα,p is also defined as a coding over a two-letter alphabet of the orbit of point ρ under the action of the irrational rotation Rα : x → x + α (mod 1). A substitution fixes a Sturmian word if and only if it is invertible. The main object of the present paper is to investigate Rauzy fractals associated with two-letter invertible substitutions. As an application, we give...

On the length of the continued fraction for values of quotients of power sums

Pietro Corvaja, Umberto Zannier (2005)

Journal de Théorie des Nombres de Bordeaux

Generalizing a result of Pourchet, we show that, if α , β are power sums over satisfying suitable necessary assumptions, the length of the continued fraction for α ( n ) / β ( n ) tends to infinity as n . This will be derived from a uniform Thue-type inequality for the rational approximations to the rational numbers α ( n ) / β ( n ) , n .

On the multiples of a badly approximable vector

Yann Bugeaud (2015)

Acta Arithmetica

Let d be a positive integer and α a real algebraic number of degree d + 1. Set α ̲ : = ( α , α ² , . . . , α d ) . It is well-known that c ( α ̲ ) : = l i m i n f q q 1 / d · | | q α ̲ | | > 0 , where ||·|| denotes the distance to the nearest integer. Furthermore, c ( α ̲ ) n - 1 / d c ( n α ̲ ) n c ( α ̲ ) for any integer n ≥ 1. Our main result asserts that there exists a real number C, depending only on α, such that c ( n α ̲ ) C n - 1 / d for any integer n ≥ 1.

On the period length of some special continued fractions

R. A. Mollin, H. C. Williams (1992)

Journal de théorie des nombres de Bordeaux

We investigate and refine a device which we introduced in [3] for the study of continued fractions. This allows us to more easily compute the period lengths of certain continued fractions and it can be used to suggest some aspects of the cycle structure (see [1]) within the period of certain continued fractions related to underlying real quadratic fields.

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