Square matrix whose entries are 1 along the anti-diagonal and 0 elsewhere
In mathematics, especially linear algebra, the exchange matrices (also called the reversal matrix, backward identity, or standard involutory permutation) are special cases of permutation matrices, where the 1 elements reside on the antidiagonal and all other elements are zero. In other words, they are 'row-reversed' or 'column-reversed' versions of the identity matrix.[1]
Any matrix A satisfying the condition AJ = JA is said to be centrosymmetric.
Any matrix A satisfying the condition AJ = JAT is said to be persymmetric.
Symmetric matrices A that satisfy the condition AJ = JA are called bisymmetric matrices. Bisymmetric matrices are both centrosymmetric and persymmetric.
See also
Pauli matrices (the first Pauli matrix is a 2×2 exchange matrix)
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