Quadratic form (statistics)

In multivariate statistics, if ${\displaystyle \epsilon }$ is a vector of ${\displaystyle n}$ random variables, and ${\displaystyle \Lambda }$ is an ${\displaystyle n}$-dimensional symmetric matrix, then the scalar quantity ${\displaystyle \epsilon ^{T}\Lambda \epsilon }$ is known as a quadratic form in ${\displaystyle \epsilon }$.

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