BBP transition     random-matrices

Leonid Petrov


This simulation uses WebAssembly and the Eigen library to compute eigenvalues of a (modified) Gaussian Orthogonal Ensemble (GOE) matrix. We introduce a rank-1 perturbation governed by a parameter $\theta$: $$A\mapsto A + \theta \cdot e_1e_1^T,$$ where $A$ is the original GOE matrix, and $e_1$ is the first basis vector. There is the BBP phase transition phenomenon: for large enough $|\theta|$, the top eigenvalue “spikes” out of the traditional GOE spectrum.

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Upper 10×10 Corner of Matrix:
Lowest 5 Eigenvalues:
5 Eigenvalues around zero:
Top 5 Eigenvalues:
Lowest 10 Eigenvalues:
20 Eigenvalues Around Zero:
Top 10 Eigenvalues:
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Histogram of eigenvalues:

code

(note: parameters in the code might differ from the ones in simulation results below)