— In this paper, we perform a complete asymptotic performance analysis of the stochastic approximation algorithm (denoted subspace network learning algorithm) derived from Oja’s learning equation, in the case where the learning rate is constant and a large number of patterns is available. This algorithm drives the connection weight matrix WWW to an orthonormal basis of a dominant invariant subspace of a covariance matrix. Our approach consists in associating to this algorithm a second stochastic approximation algorithm that governs the evolution of WWWWWWT to the projection matrix onto this dominant invariant subspace. Then, using a general result of Gaussian approximation theory, we derive the asymptotic distribution of the estimated projection matrix. Closed form expressions of the asymptotic covariance of the projection matrix estimated by the SNL algorithm, and by the smoothed SNL algorithm that we introduce, are given in case of independent or correlated learning patterns and ...