Two new on-line recursive algorithms, namely, the Jacobi recursive pri
ncipal component algorithm (JRPCA) and the Gauss-Seidel recursive prin
cipal component algorithm (GRPCA), are introduced for the computation
of principal components of a slowly varying nonstationary vector stoch
astic process. By using these algorithms, the principal components can
be adaptively estimated. The speed of convergence of the proposed alg
orithms is also discussed. Simulation results show that the proposed a
lgorithms have a faster speed of convergence and a better adaptivity w
hen compared to other existing methods.