Multi-index notation
= Multi-index notation
{title2=$\alpha=(\alpha_1,\ldots,\alpha_n)$}
{wiki}
A multi-index is a tuple of nonnegative integers used to abbreviate products and partial derivatives: $|\alpha|=\sum_j\alpha_j$, $x^\alpha=\prod_jx_j^{\alpha_j}$, and $D^\alpha=\prod_jD_j^{\alpha_j}$.
= Multi-index
{synonym}