Dissimilarity matrix
= Dissimilarity matrix
{title2=$D_{rt}=d(x_r,x_t)$}
A dissimilarity matrix records pairwise separation of observations or profiles. Usually it is symmetric, nonnegative and zero on the diagonal. A <metric space> additionally requires the triangle inequality and separation of distinct profiles. <Agglomerative hierarchical clustering> can be applied to many dissimilarity matrices that are not Euclidean distance matrices; the claimed geometry must be checked separately.