Một giới hạn dưới chính xác cho các tích phân elliptic toàn phần loại một

Zhen-Hang Yang1,2, Jing-Feng Tian3, Ya-Ru Zhu3
1Engineering Research Center of Intelligent Computing for Complex Energy Systems of Ministry of Education, North China Electric Power University, Baoding, People’s Republic of China
2Zhejiang Electric Power Company Research Institute, Hangzhou, People’s Republic of China
3Department of Mathematics and Physics, North China Electric Power University, Baoding, People’s Republic of China

Tóm tắt

Gọi $${\mathcal {K}}\left( r\right) $$ là các tích phân elliptic toàn phần loại một và $$\text{ arth }r$$ biểu thị hàm tang hỗn hợp ngược. Chúng tôi chứng minh rằng bất đẳng thức $$\begin{aligned} \frac{2}{\pi }{\mathcal {K}}\left( r\right) >\left[ 1-\lambda +\lambda \left( \frac{\text{ arth }r}{r}\right) ^{q}\right] ^{1/q} \end{aligned}$$ tồn tại cho $$r\in \left( 0,1\right) $$ với các hằng số tốt nhất $$\lambda =3/4$$ và $$q=1/10$$. Điều này cải tiến một số kết quả đã biết và đưa ra câu trả lời tích cực cho một giả thuyết về giới hạn trên tốt nhất cho trung bình hình học – số học Gaussian theo các trung bình logarit và số học.

Từ khóa

#hàm elliptic toàn phần #bất đẳng thức #hàm tang hỗn hợp ngược #trung bình hình học #trung bình số học

Tài liệu tham khảo

Borwein, J.M., Borwein, P.B.: Pi and the AGM. Wiley, New York (1987) Whittaker, E.T., Watson, G.N.: A Course of Modern Analysis, 4th edn. Cambridge University Press, London (1958) Carlson, B.C., Vuorinen, M.: Inequality of the AGM and the logarithmic mean. SIAM. Rev. 33, 655 (1991). (Problem 91–117) Todd, J., Braden, B., Danloy, B., Schmidt, F.: Inequality of the AGM and the logarithmic Mean (B. C. Carlson and M. Vuorinen). SIAM. Rev. 34(4), 653–654 (1992) Sándor, J.: On certain inequalities for means. J. Math. Anal. Appl. 189, 602–606 (1995) Bracken, P.: An arithmetic–geometric mean inequality. Exposition. Math. 19, 273–279 (2001) Neuman, E., Sándor, J.: On certain means of two arguments and their extensions. Int. J. Math. Math. Sci. 16, 981–993 (2003) Qi, F., Sofo, A.: An alternative and united proof of a double inequality for bounding the arithmetic-geometric mean. http://arxiv.org/pdf/0902.2515v1.pdf Yang, Z.-H.: A new proof of inequalities for Gauss compound mean. Int. J. Math. Anal. 4(21), 1013–1018 (2010) Anderson, G.D., Vamanamurthy, M.K., Vuorinen, M.: Functional inequalities for hypergeometric functions and complete elliptic integrals. SIAM J. Math. Anal. 23, 512–524 (1992) Vamanamurthy, M.K., Vuorinen, M.: Inequalities for means. J. Math. Anal. Appl. 183(1), 155–166 (1994) Borwein, J.M., Borwein, P.B.: Inequalities for compound mean iterations with logarithmic asymptotes. J. Math. Anal. Appl. 177(2), 572–582 (1993) Yang, Z.-H., Song, Y.-Q., Chu, Y.-M.: Sharp bounds for the arithmetic-geometric mean. J. Inequal. Appl. 2014, 192 (2014) Alzer, H., Qiu, S.-L.: Monotonicity theorems and inequalities for the complete elliptic integrals. J. Comput. Appl. Math. 172, 289–312 (2004) Yang, Z.-H., Qian, W.-M., Chu, Y.-M., Zhang, W.: On approximating the arithmetic-geometric mean and complete elliptic integral of the first kind. J. Math. Anal. Appl. 462, 1714–1726 (2018) Qian, W.-M., He, Z.-Y., Chu, Y.-M.: Approximation for the complete elliptic integral of the first kind. Rev. R. Acad. Cienc. Exactas Fís. Nat. Ser. A Mat. 114(2), 12 (2020). (Article ID 57) Borwein, J.M., Borwein, P.B.: The arithmetic–geometric mean and fast computation of elementary functions. SIAM Rev. 26, 351–366 (1984) Carlson, B.C., Guatafson, J.L.: Asymptotic expansion of the first elliptic integral. SIAM J. Math. Anal. 16(5), 1072–1092 (1985) Anderson, G.D., Vamanamurthy, M.K., Vuorinen, M.: Functional inequalities for complete elliptic integrals and their ratios. SIAM J. Math. Anal. 21, 536–549 (1990) Kühnau, R.: Eine Methode, die Positivitä t einer Funktion zu prüfen. Z. Angew. Math. Mech. 74, 140–143 (1994). (in German) Qiu, S.-L., Vamanamurthy, M.K.: Sharp estimates for complete elliptic integrals. SIAM. J. Math. Anal. 27(3), 823–834 (1996) Alzer, H.: Sharp inequalities for the complete elliptic integral of the first kind. Math. Proc. Camb. Philos. Soc. 124(2), 309–314 (1998) Qiu, S.-L., Vuorinen, M.: Landen inequalities for hypergeometric functions. Nagoya Math. J. 154, 31–56 (1999) Wang, M.-K., Chu, Y.-M., Qiu, S.-L.: Some monotonicity properties of generalized ellipitic integrals with applications. Math. Inequal. Appl. 16(3), 671–677 (2013) Wang, M.-K., Chu, Y.-M., Qiu, S.-L.: Sharp bounds for generalized elliptic integrals of the first kind. J. Math. Anal. Appl. 429, 744–757 (2015) Yang, Z.-H., Chu, Y.-M.: A monotonicity property involving the generalized elliptic integrals of the first kind. Math. Inequal. Appl. 20(3), 729–735 (2017) Yang, Z.-H., Qian, W.-M., Chu, Y.-M.: Monotonicity properties and bounds involving the complete elliptic integrals of the first kind. Math. Inequal. Appl. 21(4), 1185–1199 (2018) Wang, M.K., Zhang, W., Chu, Y.M.: Monotonicity, convexity and inequalities involving the generalized elliptic integrals. Acta Math. Sci. Ser. B (Engl. Ed.) 39(5), 1440–1450 (2019) Yang, Z.-H., Tian, J.: Sharp inequalities for the generalized elliptic integrals of the first kind. Ramanujan J. 48, 91–116 (2019) Yang, Z.-H., Tian, J.: Convesity and monotonicity for elliptic integrals of the first kind and applications. Appl. Anal. Discret. Math. 13, 240–260 (2019) Wang, M.K., Chu, Y.M., Zhang, W.: Monotonicity and inequalities involving zero-balanced hypergeometric function. Math. Inequal. Appl. 22(2), 601–617 (2019) Wang, M.-K., Zhang, W., Chu, Y.-M.: Monotonicity, convexity and inequalities involving the generalized elliptic integrals. Acta Math. Sci. 39B(5), 1440–1450 (2019) Wang, M.-K., Chu, H.-H., Li, Y.-M., Chu, Y.-M.: Answers to three conjectures on convexity of three functions involving complete elliptic integrals of the firrst kind. Appl. Anal. Discret. Math. 14(1), 255–271 (2020) Yang, Z.-H., Qian, W.-M., Zhang, W., Chu, Y.-M.: Notes on the complete elliptic integral of the first kind. Math. Inequal. Appl. 23(1), 77–93 (2020) Anderson, G.D., Vamanamurthy, M.K., Vuorinen, M.: Conformal Invariants, Inequalities, and Quasiconformal Maps. Wiley, New York (1997) Ponnusamy, S., Vuorinen, M.: Asymptotic expansions and inequalities for hypergeometric functions. Mathematika 44, 278–301 (1997) Heikkala, V., Lindén, H., Vamanamurthy, M.K., Vuorinen, M.: Generalized elliptic integrals and the Legendre M-function. J. Math. Anal. Appl. 338(2), 223–243 (2008) Heikkala, V., Vamanamurthy, M.K., Vuorinen, M.: Generalized elliptic integrals. Comput. Methods Funct. Theory 9(1), 75–109 (2009) Neuman, E.: Inequalities and bounds for generalized complete elliptic integrals. J. Math. Anal. Appl. 373(1), 203–213 (2011) Wang, M.-K., Chu, Y.-M., Jiang, Y.-P.: Ramanujan’s cubic transformation inequalities for zero-balanced hypergeometric functions. Rocky Mt. J. Math. 46(2), 679–691 (2016) Wang, M.-K., He, Z.-Y., Chu, Y.-M.: Sharp power mean inequalities for the generalized elliptic integral of the first Kind. Comput. Methods Funct. Theory 20(1), 111–124 (2020) Zhao, T.-H., Wang, M.-K., Chu, Y.-M.: A sharp double inequality involving generalized complete elliptic integral of the first kind. AIMS Math. 5(5), 4512–4528 (2020) Belzunce, F., Ortega, E., Ruiz, J.M.: On non-monotonic ageing properties from the Laplace transform, with actuarial applications. Insurance Math. Econom. 40, 1–14 (2007) Yang, Z.-H., Chu, Y.-M., Tao, X.-J.: A double inequality for the trigamma function and its applications. Abstr. Appl. Anal. 9, 2014 (2014). (Art, ID 702718 ) Yang, Z.-H., Chu, Y.-M., Zhang, X.-H.: Necessary and sufficient conditions for functions involving the psi function to be completely monotonic. J. Inequal. Appl. 2015, 157 (2015) Yang, Z.-H., Chu, Y.-M.: Inequalities for certain means in two arguments. J. Inequal. Appl. 2015, 299 (2015) Yang, Z.-H., Qian, W.-M., Chu, Y.-M., Zhang, W.: On rational bounds for the gamma function. J. Inequal. Appl. 2017, 210 (2017) Yang, Z.-H., Tian, J.: Monotonicity and sharp inequalities related to gamma function. J. Math. Inequal. 12(1), 1–22 (2018) Yang, Z.-H., Tian, J.-F.: Windschitl type approximation formulas for the gamma function. J. Inequal. Appl. 2018, 272 (2018) Yang, Z.-H., Tian, J.-F.: An accurate approximation formula for gamma function. J. Inequal. Appl. 2018, 56 (2018) Yang, Z.-H., Qian, W.-M., Chu, Y.-M., Zhang, W.: On approximating the error function. Math. Inequal. App. 21(2), 469–479 (2019) Yang, Z.-H.: Sharp approximations for the complete elliptic integrals of the second kind by one-parameter means. J. Math. Anal. Appl. 467, 446–461 (2018) Yang, Z.-H., Chu, Y.-M., Zhang, W.: High accuracy asymptotic bounds for the complete elliptic integral of the second kind. Appl. Math. Comput. 348, 552–564 (2019) Lv, H.-L., Yang, Z.-H., Zheng, S.: Monotonicity and inequalities involving the incomplete gamma function. J. Math. Inequal. 13(2), 351–367 (2019) Yang, Z., Tian, J.-F.: Monotonicity rules for the ratio of two Laplace transforms with applications. J. Math. Anal. Appl. 470, 821–845 (2019) Yang, Z.-H., Tian, J.: Convesity and monotonicity for elliptic integrals of the first kind and applications. https://arxiv.org/abs/1705.05703 Yang, Z.-H., Tian, J.-F., Zhu, Y.-R.: A rational approximation for the complete elliptic integrals. Math. 8, 635 (2020)