Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Identity for the Product of Two Positive Definite Quadratic Forms

Abstract

THE problem of generalizing the following basic identity given in Hardy, Littlewood and Pólya1, remains to be considered. We shall show that the generalized Cauchy inequality follows immediately from this generalization. The resulting identity has many fruitful applications in problems of multivariate ratio estimation in sample survey theory.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Similar content being viewed by others

References

  1. Hardy, G. H., Littlewood, J. E., and Pólya, G., in Inequalities (Cambridge University Press, 1934).

    MATH  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

KOOP, J., GRAY, G. Identity for the Product of Two Positive Definite Quadratic Forms. Nature 216, 304 (1967). https://doi.org/10.1038/216304a0

Download citation

  • Received:

  • Issue date:

  • DOI: https://doi.org/10.1038/216304a0

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing