 This implies that two distinct rows of a Hadamard matrix differ in exactly "n"/2 positions, and, since negation of a row does not affect orthogonality, that any row of "H" differs from any row of −"H" in "n"/2 positions as well, except when the rows correspond, in which case they differ in "n" positions.To get the augmented Hadamard code above with formula_55, the chosen Hadamard matrix "H" has to be of Sylvester type, which gives rise to a message length of formula_56.The distance of a code is the minimum Hamming distance between any two distinct codewords, i.e., the minimum number of positions at which two distinct codewords differ.