Absolute value of the scalar product, |s_ℓ,1| (1), of the first PC eigenvector with the 200-dimension hyperdiagonal unitary vector as a function of the trial period in the case of the Crab pulsar. The scalar product (when a high signal-to-noise ratio is available) reaches magnitude i in a plateau region. Eigenvalue and scalar are plotted together in Fig. 15. The period P_PCA was computed with the first PC eigenvalue, Fig. 6.