Application of solutions to the Thiele–Hermite problem for expanding the functions tg $z$, ctg $z$, th $z$, and cth $z$, in continued fractions

Authors

  • Yu. Myslo Uzhhorod National University
  • M. Pahirya Uzhhorod National University

DOI:

https://doi.org/10.3842/umzh.v78i9-10.9920

Keywords:

continued fractions, expanding functions into continued fractions

Abstract

UDC 517.518:519.652

A function of one complex variable can be expanded into a continued fraction by using one of the well-known methods based either on the Riccati differential equation, or on the Gauss hypergeometric series, or on the Hankel determinants, or on the reciprocal  Thiele derivatives. The possibility of application of the solutions to the Thiele–Hermite problem with an aim of finding the coefficients of  expansions of the functions tg $z$, ctg $z$, th $z$, and cth $z$ into continued fractions is analyzed.

References

1. V. K. Dzyadyk, I. A. Shevchuk, Theory of uniform approximation of functions by polynomials, Walter de Gruyter GmbH & Co. KG, Berlin (2008). DOI: https://doi.org/10.1515/9783110208245

2. І. П. Гаврилюк, В. Л. Макаров, Методи обчислень, ч. 1, Вища школа, Київ (1995).

3. J. L. Walsh, Interpolation and approximation by rational functions in the complex domain, Amer. Math. Soc. Colloq. Publ., Vol. XX, American Mathematical Society, Providence, RI (1960).

4. G. A. Baker, P. Graves-Morris, Padé approximants, Addison-Wesley, London (1981).

5. A. N. Khovanskii, The application of continued fractions and their generalizations to problems in approximation theory, P. Noordhoff, Groningen (1963).

6. W. B. Jones, W. J. Thron, Continued fractions. Analytic theory and applications, Addison-Wesley Publ. Co., Reading, MA (1980).

7. A. Cuyt, V. Brevik Petersen, B. Verdonk, H. Waadeland, W. B. Jones, Handbook of continued fractions for special functions, Springer, New York (2008).

8. М. Пагіря, Наближення функцій ланцюговими дробами, Ґражда, Ужгород (2016).

9. M. Abramowitz, I. A. Stegun, Handbook of mathematical functions with formulas, graphs, and mathematical tables, National Bureau of Standards Applied Mathematics Series, Vol. 55, U.S. Government Printing Office, Washington, DC (1964). DOI: https://doi.org/10.1115/1.3625776

10. T. N. Thiele, Interpolationsrechnung, B. G. Teubner, Leipzig (1909).

11. N. E. Nörlund, Vorlesungen über Differenzenrechnung, Springer, Berlin (1924). DOI: https://doi.org/10.1007/978-3-642-50824-0

12. Yu. Myslo, M. Pahirya, Osculatory interpolating Thiele continued fraction, Proc. Int. Geom. Cent., 15, № 2, 138–160 (2022).

13. Yu. Myslo, M. Pahirya, A certain method of construction of Thiele–Hermite continued fraction at a point, Proc. Int. Geom. Cent., 16, № 3--4, 244–261 (2023). DOI: https://doi.org/10.15673/pigc.v16i3.2646

14. R. K. Morley, Brief notes and comments. Successive derivatives of (tan x), Nat. Math. Mag., 19, № 6, 311–312 (1945).

15. P. Henrici, P. Pfluger, Truncation error estimates for Stieltjes fractions, Numer. Math., 9, 120–138 (1966). DOI: https://doi.org/10.1007/BF02166031

16. F. B. Hildebrand, Introduction to numerical analysis, Dover Publications, New York (1987).

17. P. Henrici, Applied and computational complex analysis. Vol. 1: Power series, integration, conformal mapping, location of zeros, Wiley-Interscience, New York, London, Sydney (1974).

18. S. Sanielevici, Sur l'intégration des équations différentielles par les fractions continues, Ann. Sci. Univ. Jassy, 18, 197–214 (1933).

19. K. D. Cooper, S. C. Cooper, W. B. Jones, More on $C$-fraction solutions to Riccati equations, Rocky Mountain J. Math., 21, № 2, 139–158 (1991). DOI: https://doi.org/10.1216/rmjm/1181073000

20. A. N. Stokes, Continued fraction solutions of the Riccati equation, Bull. Austral. Math. Soc., 25, № 2, 207–214 (1982). DOI: https://doi.org/10.1017/S0004972700005219

21. E. P. Merkes, W. T. Scott, Continued fraction solution of the Riccati equation, J. Math. Anal. Appl., 4, 309–327 (1962). DOI: https://doi.org/10.1016/0022-247X(62)90057-4

Published

25.09.2026

Issue

Section

Research articles