多重指数
x α := x 1 α 1 x 2 α 2 ⋯ x n α n . {\displaystyle x^{\alpha }:=x_{1}^{\alpha _{1}}x_{2}^{\alpha _{2}}\dotsb x_{n}^{\alpha _{n}}.} ただし x = ( x 1 , x 2 , ... , x n ) ∈ R n . {\displaystyle x=(x_{1},x_{2},\ldots ,x_{n})\in \mathbb {R} ^{n}.}