Then a specific metric is involved, sometimes we want to automatically add it to products.

E.g., in a context considering the common Minkowski inner product matrix where the $η$ 4x4 matrix and $μ$ is a vector in $R_{4}$
which leads to the change of sign of some terms.

$x_{μ}x_{μ}=x_{μ}η_{μν}x_{ν}=−x_{0}+x_{1}+x_{2}+x_{3};$

## Articles by others on the same topic (0)

There are currently no matching articles.