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A mini-gap theorem for Fourier series

Published online by Cambridge University Press:  24 October 2008

W. K. Hayman
Affiliation:
Imperial College, London

Extract

Suppose that

belongs to L2( − π, π). If most of the coefficients vanish then f (x) cannot be too small in a certain interval without being small generally. More precisely Ingham ((2), Theorem 1) has proved the following

THEOREM A. Suppose that f (x) is given by (1·1) and that an = 0, except for a sequence n = nν, where nν+1nνC. Then given ∈ > 0 there exists a constant A (∈), such that we have for any real x1

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1968

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References

REFERENCES

(1)Hayman, W. K.Mean p -valent functions with mini-gaps. Math. Nachr. (to be published).Google Scholar
(2)Ingham, A. E.Some trigonometrical inequalities with applications to the theory of series. Math. Z. 41 (1936), 367379.CrossRefGoogle Scholar
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