Anti-diagonal matrix

An anti-diagonal matrix (also known as a skew-diagonal matrix) is a type of square matrix where the entries are non-zero only on the anti-diagonal, which runs from the top right corner to the bottom left corner of the matrix. In other words, for an \( n \times n \) matrix \( A \), the entry \( a_{ij} \) is non-zero if and only if \( i + j = n + 1 \).