
arXiv: 1009.3921
We prove generalizations of Löwner's results on matrix monotone functions to several variables. We give a characterization of when a function of $d$ variables is locally monotone on $d$-tuples of commuting self-adjoint $n$-by-$n$ matrices. We prove a generalization to several variables of Nevanlinna's theorem describing analytic functions that map the upper half-plane to itself and satisfy a growth condition. We use this to characterize all rational functions of two variables that are operator monotone.
Functional calculus for linear operators, edge of the wedge, mathematics, Mathematics - Complex Variables, Several-variable operator theory (spectral, Fredholm, etc.), Loewner's theorem, functional calculus, operator monotone functions, Functional Analysis (math.FA), matrix monotone functions, Mathematics - Functional Analysis, 47A63, 32A35, edge of the wedge theorem, FOS: Mathematics, Norms of matrices, numerical range, applications of functional analysis to matrix theory, monotone operators, loewner class, Linear operator inequalities, loewner's theorem, Loewner class, Complex Variables (math.CV), Analysis
Functional calculus for linear operators, edge of the wedge, mathematics, Mathematics - Complex Variables, Several-variable operator theory (spectral, Fredholm, etc.), Loewner's theorem, functional calculus, operator monotone functions, Functional Analysis (math.FA), matrix monotone functions, Mathematics - Functional Analysis, 47A63, 32A35, edge of the wedge theorem, FOS: Mathematics, Norms of matrices, numerical range, applications of functional analysis to matrix theory, monotone operators, loewner class, Linear operator inequalities, loewner's theorem, Loewner class, Complex Variables (math.CV), Analysis
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