Fuente TeX:

A = PDP^{-1} = P D^{\frac{1}{2}} D^{\frac{1}{2}} P^{-1} = P D^{\frac{1}{2}} P^{-1}P D^{\frac{1}{2}} P^{-1}= ( P D^{\frac{1}{2}} P^{-1} )^{2}