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Asymptotic solutions to linear differential equations with coefficients of the power order of growth, 2

Published online by Cambridge University Press:  14 November 2011

M. H. Lantsman
Affiliation:
Department of Mathematics, Ail-Union Correspondence Civil-Engineering Institute, Moscow 109029, U.S.S.R

Synopsis

We consider linear differential equations of the form F(x, z)≡ xn + a1(z)x(n-1)+…+an(z)x = 0 with power-logarithmic coefficients or coefficients which are asymptotically similar to power-logarithmic functions in a central sector S of a complex plane for z →∞, z∈S. The main result of this paper is that in a sufficiently small central sector SE⊂S there is a fundamental system of solutions {xi(z) = exp [∫γi(z)dz)} where each function γi(z) is equivalent to a power-logarithmic function or has an estimate of the form O(z−∞). Furthermore, a precise estimate is obtained for a partial solution of a nonhomogeneous equation F(x, z) = α(z), where the function α(z) grows like a power.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1985

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References

1Lantsman, M. H.. Asymptotic solutions to linear differential equations with coefficients of the power order of growth, 1. Proc. Roy. Soc. Edinburgh Sect. A 100 (1985), 301326.Google Scholar
2Devinatz, A.. The deficiency index of certain fourth-order ordinary self-adjoint differential operators. Quart. J. Math. Oxford 23 (1972), 267286.CrossRefGoogle Scholar
3Lantsman, M. H.. Asymptotic integration of some linear differential equations. Math. Nachr. 121 (1985), 163177.Google Scholar