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Some formulae of P. Stein and others concerning trigonometrical sums

Published online by Cambridge University Press:  24 October 2008

N. B. Slater
Affiliation:
University of Leeds

Extract

Let

where the frequencies vr are strictly positive and the amplitudes ar are non-zero; and let

be the number of zeros of f(t) – a for 0 ≤ t < T. In physical problems, where f(t) may represent, for example, a general coordinate in a vibrating dynamical system or a set of alternating currents in a cable, formulae are required for the frequency with which f(t) passes through a given value a; that is, for asymptotic or average values of Ga/T. The purpose here is to collect such formulae, and to sketch their background and relations in a way which may suggest extensions. The writer is particularly indebted to Prof. P. Stein for a manuscript containing new results (SI-V in §§2 and 5 below) and for his permission to publish them without his original proofs; these proofs were extensions of the method he gave (6) for the case n = 2.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1954

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References

REFERENCES

(1)Kac, M.Amer. J. Math. 65 (1943), 609. (See also some corrigenda in Proc. Land. math. Soc. (2), 50 (1949), 390.)CrossRefGoogle Scholar
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