Convex maps on $\protect \mathbb{R}^n$ and positive definite matrices

We obtain several convexity statements involving positive definite matrices. In particular, if $A,B,X,Y$ are invertible matrices and $A,B$ are positive, we show that the map \[ (s,t) \mapsto \mathrm{Tr}\,\log \left(X^*A^sX + Y^*B^tY\right) \] is jointly convex on $\mathbb{R}^2$. This is related to s...

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Bibliographic Details
Main Authors: Bourin, Jean-Christophe, Shao, Jingjing
Format: Article
Language:English
Published: Académie des sciences 2020-10-01
Series:Comptes Rendus. Mathématique
Online Access:https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.25/