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JOURNALS // Izvestiya Vysshikh Uchebnykh Zavedenii. Matematika // Archive

Izv. Vyssh. Uchebn. Zaved. Mat., 2022 Number 7, Pages 3–9 (Mi ivm9788)

This article is cited in 1 paper

The inverse problem for generalized contraharmonic means

T. H. Dinha, C. T. Leb, B. K. Voc

a Troy University, Troy, AL, 36072 USA
b Quy Nhon University, Viet Nam
c University of Finance and Marketing, Ho Chi Minh City, Viet Nam

Abstract: In this paper we introduce the generalized contraharmanic mean associated to a Kubo-Ando mean $\sigma$ as
$$ C_\sigma(X, Y) = X\sigma Y - X\sigma^\perp Y, $$
where $\sigma^\perp$ is the dual mean of $\sigma$ and $X, Y$ are positive definite matrices. We show that for a symmetric Kubo-Ando mean $\sigma$ such as $\sigma \ge \sharp$ and for any positive definite matrices $A \ge B$ the inverse problem
\begin{equation*} A=C_\sigma(X, Y), \ \ B=X^{1/2}(X^{-1/2}YX^{-1/2})^{1/2}X^{1/2} \end{equation*}
has a positive solution $(X, Y)$.

Keywords: Kubo-Ando means, geometric mean, generalized contraharmonic mean, inverse problem, Brouwer's fixed point theorem, non-linear matrix equations.

UDC: 517

Received: 13.10.2021
Revised: 17.05.2022
Accepted: 29.06.2022

DOI: 10.26907/0021-3446-2022-7-3-9


 English version:
Russian Mathematics (Izvestiya VUZ. Matematika), 2022, 66:7, 1–6


© Steklov Math. Inst. of RAS, 2024