Structure of Hiai–Petz parametrized geometry for positive definite matrices

Recently Hiai–Petz (2009) [10], discussed a parametrized geometry for positive definite matrices with a pull-back metric for a diffeomorphism to the Euclidean space. Though they also showed that the geodesic is a path of operator means, their interest lies mainly in metrics of the geometry. In this paper, we reconstruct their geometry without metrics and then we show their metric for each unitarily invariant norm defines a Finsler one. Also we discuss another type of geometry in Hiai and Petz (2009) [10], which is a generalization of Corach–Porta–Recht’s one [3].