positive semidefinitePositiveSemidefinite2002-02-15 02:48:352002-02-15 02:58:36Definition%\usepackage{graphicx}
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\newcommand{\mathbb}[1]{\mathbbmss{#1}}Let $A$ be an $n\times n$ symmetric real square matrix. If for any non-zero vector $x$ we have
$$x^t Ax\geq 0,$$
we call $A$ a \emph{positive semidefinite} matrix.