orígen TeX:

d_{m}\left(\underset{\sim}{x}_{i},\underset{\sim}{x}_{j}\right)=\sqrt{\left(\underset{\sim}{x}_{i}-\underset{\sim}{x}_{j}\right)^{t}\sum^{-1}\left(\underset{\sim}{x}_{i}-\underset{\sim}{x}_{j}\right)}