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Weyl almost-periodic functions

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The class of complex-valued functions , , summable to degree on each bounded interval of the real axis and such that for every there is an for which has a relatively-dense set of -almost-periods (cf. Almost-period). The class was defined by H. Weyl [1]. The class of Weyl almost-periodic functions is an extension of the class of Stepanov almost-periodic functions.

Weyl almost-periodic functions are related to the metric

If is a null function in the metric , i.e.

and is a Stepanov almost-periodic function, then

(*)

is a Weyl almost-periodic function. There also exist Weyl almost-periodic functions which cannot be represented in the form (*); cf. [3].

References

[1] H. Weyl, "Integralgleichungen und fastperiodische Funktionen" Math. Ann. , 97 (1927) pp. 338–356
[2] B.M. Levitan, "Almost-periodic functions" , Moscow (1953) (In Russian)
[3] B.M. Levitan, V.V. Stepanov, "Sur les fonctions presque périodiques apportenant au sens strict à la classe " Dokl. Akad. Nauk SSSR , 22 : 5 (1939) pp. 220–223
How to Cite This Entry:
Weyl almost-periodic functions. E.A. Bredikhina (originator), Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Weyl_almost-periodic_functions&oldid=16250
This text originally appeared in Encyclopedia of Mathematics - ISBN 1402006098