Antisymmetric Matrix Diagonal

Alejandro Mascort

November 7, 2024

Prove that diagonal elements of an antisymmetric matrix are zero.

Show Solution

As we know, an antisymmetric matrix AA satisfies the property AT=AA^T = -A. Let’s consider the diagonal elements of AA denoted by aiia_{ii}.

According to the definition of the transpose, the diagonal elements of ATA^T are given by aiiT=aiia_{ii}^T = a_{ii}. Since AT=AA^T = -A, we have aii=aiia_{ii} = -a_{ii}.

Solving this equation, we find that aii=0a_{ii} = 0 for all ii. Therefore, the diagonal elements of an antisymmetric matrix are zero.