Skip to main content

Advertisement

Log in

Improved Approximation Formulas and Inequalities for the Wallis Ratio

  • Original Paper
  • Published:
Bulletin of the Iranian Mathematical Society Aims and scope Submit manuscript

Abstract

In this paper, we present a new approximation of the Wallis ratio. This approximation is fast in comparison with the recently discovered asymptotic series. We also establish the inequalities related to this approximation. Finally, some numerical computations are provided for demonstrating the superiority of our approximation over other classical ones.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

References

  1. Chen, C.P., Qi, F.: Completely monotonic function associated with the gamma functions and proof of Wallis inequality. Tamkang J. Math. 36(4), 303–307 (2005)

    MathSciNet  MATH  Google Scholar 

  2. Chen, C.P., Qi, F.: The best bounds in Wallis inequality. Proc. Am. Math. Soc. 133(2), 397–401 (2005)

    Article  MathSciNet  MATH  Google Scholar 

  3. Qi, F.: Integral representations and complete monotonicity related to the remainder of Burnsides formula for the gamma function. J. Comput. Appl. Math. 268, 155–167 (2014)

    Article  MathSciNet  MATH  Google Scholar 

  4. Qi, F., Cui, L.H., Xu, S.L.: Some inequalities constructed by Tchebysheff’s integral inequality. Math. Inequal. Appl. 2(4), 517–528 (1999)

    MathSciNet  MATH  Google Scholar 

  5. Guo, S., Xu, J.G., Qi, F.: Some exact constants for the approximation of the quantity in the Wallis formula. J. Inequal. Appl. 2013(67) (2013)

  6. Qi, F., Mortici, C.: Some best approximation formulas and inequalities for the Wallis ratio. Appl. Math. Comput. 253, 363–368 (2015)

    MathSciNet  MATH  Google Scholar 

  7. Cao, X.D., Xu, H.M., You, X.: Multiple-correction and faster approximation. J. Number Theory 149, 327–350 (2015)

    Article  MathSciNet  MATH  Google Scholar 

  8. Cao, X.D.: Multiple-correction and continued fraction approximation. J. Math. Anal. Appl. 424, 1425–1446 (2015)

    Article  MathSciNet  MATH  Google Scholar 

  9. Cao, X.D., You, X.: Multiple-correction and continued fraction approximation (II). Appl. Math. Comput. 261, 192–205 (2015)

    MathSciNet  MATH  Google Scholar 

  10. Mortici, C.: Product approximations via asymptotic integration. Am. Math. Mon. 117(5), 434–441 (2010)

    Article  MathSciNet  MATH  Google Scholar 

  11. Mortici, C.: New improvements of the Stirling formula. Appl. Math. Comput. 217(2), 699–704 (2010)

    MathSciNet  MATH  Google Scholar 

  12. Mortici, C.: A continued fraction approximation of the gamma function. J. Math. Anal. Appl. 402, 405–410 (2013)

    Article  MathSciNet  MATH  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Xu You.

Additional information

Communicated by Bamdad Yahaghi.

This work was supported by the National Natural Science Foundation of China (Grant nos. 11571267, 61403034 and 91538112), and NSAF under Grant U1830107, and Beijing Municipal Commission of Education Science and Technology Program KM201810017009.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

You, X., Chen, DR. Improved Approximation Formulas and Inequalities for the Wallis Ratio. Bull. Iran. Math. Soc. 45, 783–789 (2019). https://doi.org/10.1007/s41980-018-0165-z

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s41980-018-0165-z

Keywords

Mathematics Subject Classification

Navigation