Hadamard matrix

Summary

A Hadamard matrix is a square matrix with entries $\pm 1$ whose rows are pairwise orthogonal. Their determinant has absolute value $n^{n/2}$, the largest possible for a real $n \times n$ matrix with entries in $[-1, 1]$. Hadamard matrices give error-correcting codes, block designs and experimental designs. The node Hadamard matrix gives the precise definition.