English

Lyapunov exponents and eigenvalues of products of random matrices

Probability 2016-06-27 v1 Mathematical Physics Classical Analysis and ODEs math.MP

Abstract

Let X1,X2,X_1,X_2, \ldots be a sequence of i.i.di.i.d real (complex) d×dd \times d invertible random matrices with common distribution μ\mu and σ1(n),σ2(n),,σd(n)\sigma_1(n), \sigma_2(n), \ldots , \sigma_d(n) be the singular values, λ1(n),λ2(n),,λd(n)\lambda_1(n), \lambda_2(n), \ldots , \lambda_d(n) be the eigenvalues of XnXn1X1X_nX_{n-1}\cdots X_1 in the decreasing order of their absolute values for every nn. It is known that if E(log+X1)<\mathbb{E}(\log^{+}\|X_1\|)< \infty, then with probability one for all 1pd1 \leq p \leq d, limn1nlogσp(n)=γp, \lim_{n \to \infty} \frac{1}{n}\log \sigma_p(n)=\gamma_p, where γ1,γ2γd{\gamma_1,\gamma_2 \ldots \gamma_d} are the Lyapunov exponents associated with μ\mu. In this paper we show that under certain support and moment conditions on μ\mu, the absolute values of eigenvalues also exhibit the same asymptotic behaviour. In fact, a stronger asymptotic relation holds between the singular values and the eigenvalues i.e.i.e. for any r>0r>0 with probability one for all 1pd1 \leq p \leq d, limn1nrlog(λp(n)σp(n))=0, \lim_{n \to \infty} \frac{1}{n^r}\log \left(\frac{|\lambda_p(n)|}{\sigma_p(n)}\right)= 0, which implies that the fluctuations of the eigenvalues have the same asymptotic distribution as that of the corresponding singular values. Isotropic random matrices and also random matrices with i.i.di.i.d real elements, which have some finite moment and bounded density whose support contains an open set, are shown to satisfy the moment and support conditions under which the above relations hold.

Keywords

Cite

@article{arxiv.1606.07704,
  title  = {Lyapunov exponents and eigenvalues of products of random matrices},
  author = {Nanda Kishore Reddy},
  journal= {arXiv preprint arXiv:1606.07704},
  year   = {2016}
}