diagonalisation of tensors – Mathematica Stack Exchange


$$H_{(ab),(cd)} =p_{lmno}F_{lm}^{ab}G_{no}^{cd}$$
$$=p_{lmno} left(n_{do}n_{nc}+delta_{do}delta_{nc}right)left(n_{bm}delta_{la}-delta_{bm}n_{la}right)$$

Is there a way to diagonalize the above tensor using Mathematica using equation $$P^{-1}AP$$ , how to obtain $P$? $n$ is a real antisymmetric matrix and $p_{lmno}$ is an antisymmetric tensor.