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Statistics of spectral properties of matrix-valued random variables.
5
votes
Accepted
Generating a random special unitary matrix
yes, this normalization will produce a uniform distribution in ${\rm SU}(N)$, however, it might be more efficient to generate directly random matrices with unit determinant (you'll need one fewer para …
1
vote
Random matrices: why to distingusish bulk and edge cases?
there is a mathematics reason to distinguish bulk from edge, as mentioned in Ofer Zeitouni's answer, and there is a physics reason: in a physical system with an excitation gap, for example, a supercon …
1
vote
Eigenvalue distribution of low rank matrices
This is a special case of the more general problem solved in On the Exact and Approximate Eigenvalue Distribution for Sum of Wishart Matrices (2015). If all the $\alpha_i$'s are the same, the two dist …
1
vote
Is there any theoretical results about the determinants of a Non-Central Wishart matrix?
upper and lower bounds for the expectation of $\log\det W$ --- with complex matrix elements, but I presume readily generalized to real matrix elements --- have been derived in On the log-determinant o …
26
votes
Unexpected $\sqrt{3}$
this is a limit of a more general result by Majumdar and company, How many eigenvalues of a Gaussian random matrix are positive? (2010), see also their earlier papers from 2006 and 2008.
The coeffici …
1
vote
any known universality results of random matrices with non-independent entries?
the classic example is Dyson's circular ensemble of random unitary matrices (distributed uniformly with respect to the Haar measure); in the limit of large matrix size the correlation function of the …
3
votes
Accepted
Hilbert Schmidt inner product of random isotropic unitary matrices
I assume the matrices $U_1$ and $U_2$ are independently uniformly distributed in the unitary group. The product $V=U_1^HU_2$ is then itself uniformly distributed in the unitary group. The distribution …
3
votes
Random matrices having all real eigenvalues: uniform vs gaussian distributions
Real eigenvalues of non-Gaussian random matrices and their products finds that the probability that all eigenvalues are real is larger for distributions with large weight
at the origin and that decay …
5
votes
Spectral density of $D + XX^T$
The solution was obtained already by Marchkenko and Pastur, in terms of the Cauchy transform $g(z)$ of the spectral density of $D+XX^{\rm T}$, see for example equations 2 + 3 of Spectrum of deformed r …
3
votes
Functional calculation for Hermitian matrices
The $\sqrt{n}$ factors can be absorbed in the $X$ matrices, I can omit them. Consider a Hermitian matrix $X$ and a Hermitian perturbation $\delta X$. Then, for $f:\mathbb{R}\rightarrow\mathbb{R}$ one …
4
votes
Accepted
Non-asymptotic results for bulk of random Wishart matrix
You ask for the average of the singular values of the Wishart matrix. I'm pretty sure there is no closed form expression valid for any $n$. If instead you would ask for the average of the square of th …
2
votes
Accepted
A naive question about non-Hermitian random matrix
Indeed, if $A$ is non-Hermitian you cannot use the inverse $(A-z)^{-1}$ to study eigenvalues near a complex number $z$. To apply resolvent techniques to a non-Hermitian matrix $A$ you need to first sy …
8
votes
Accepted
Is there a way to simplify the following trace expression?
After a cyclic permutation of the trace, the expression you need is
$$Y=\text{tr}\left\{\mathbf{A}^HE(\mathbf{C}^H \begin{bmatrix} \mathbf{0}_{M\times M} & \mathbf{0}_{M\times N} \\ \mathbf{0}_{N\tim …
1
vote
Non-asymptotic bound on the variance of largest singular value of gaussian matrix
For a non-asymptotic result, you could just use the exact distribution of $s^2_{\rm max}$ given in Distribution of the largest eigenvalue for real Wishart and Gaussian random matrices... (Marco Chiani …
4
votes
Matrix model for "$\beta$-Ginibre" ensembles
this is not an answer to the question "what matrix model produces the eigenvalue distribution (2)", but it does explain why (2) cannot be an extrapolation between the $\beta$-Ginibre ensembles.
The e …