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1 | 1 | RandomMatrices.jl
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2 | 2 | =================
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3 | 3 |
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4 |
| -Random matrix theory repository for Julia |
| 4 | +Random matrix repository for Julia |
| 5 | + |
| 6 | +# Gaussian matrix ensembles |
| 7 | + |
| 8 | +## Joint probability density functions (jpdfs) |
| 9 | + |
| 10 | +Given eigenvalues `lambda` and the `beta` parameter of the random matrix distribution: |
| 11 | + |
| 12 | +- `VandermondeDeterminant(lambda, beta)` computes the Vandermonde determinant |
| 13 | +- `HermiteJPDF(lambda, beta)` computes the jpdf for the Hermite ensemble |
| 14 | +- `LaguerreJPDF(lambda, n, beta)` computes the jpdf for the Laguerre(n) ensemble |
| 15 | +- `JacobiJPDF(lambda, n1, n2, beta)` computes the jpdf for the Jacobi(n1, n2) ensemble |
| 16 | + |
| 17 | +## Matrix samples |
| 18 | + |
| 19 | +Constructs samples of random matrices corresponding to the classical Gaussian |
| 20 | +Hermite, Laguerre(m) and Jacobi(m1, m2) ensembles. |
| 21 | + |
| 22 | +- `GaussianHermiteMatrix(n, beta)`, `GaussianLaguerreMatrix(n, m, beta)`, |
| 23 | + `GaussianJacobiMatrix(n, m1, m2, beta)` |
| 24 | + each construct a sample dense `n`x`n` matrix for the corresponding matrix ensemble with `beta=1,2,4` |
| 25 | +- `GaussianHermiteTridiagonalMatrix(n, beta)`, `GaussianLaguerreTridiagonalMatrix(n, m, beta)`, |
| 26 | + `GaussianJacobiSparseMatrix(n, m1, m2, beta)` each construct a sparse `n`x`n` matrix for the |
| 27 | + corresponding matrix ensemble for arbitrary positive finite `beta` |
| 28 | +- `GaussianHermiteSamples(n, beta)`, `GaussianLaguerreSamples(n, m, beta)`, |
| 29 | + `GaussianJacobiSamples(n, m1, m2, beta)` return a set of `n` eigenvalues from the previous sampled |
| 30 | + random matrices |
| 31 | + |
| 32 | +(Note the parameters of the Laguerre and Jacobi ensembles are not yet defined consistently. |
| 33 | +For the first set they are integers but for the rest they are reals.) |
| 34 | + |
| 35 | +# Formal power series |
| 36 | + |
| 37 | +Allows for manipulations of formal power series (fps) and formal Laurent series. |
| 38 | + |
| 39 | +This defines the new types |
| 40 | +- `FormalPowerSeries`: power series with coefficients allowed only for non-negative integer powers |
| 41 | +- `FormalLaurentSeries`: power series with coefficients allowed for all integer powers |
| 42 | + |
| 43 | +## FormalPowerSeries |
| 44 | + |
| 45 | +In addition to basic arithmetic operations `==`, `+`, `-`, `^`, this also provides: |
| 46 | + |
| 47 | +- `tovector` returns the series coefficients |
| 48 | +- `trim` removes extraneous zeroes |
| 49 | +- `*` computes the Cauchy product (discrete convolution) |
| 50 | +- `.*` computes the Hadamard product (elementwise multiplication) |
| 51 | +- `isunit(P)` determines if `P` is a unit series |
| 52 | +- `isnonunit(P)` determines if `P` is a non-unit series |
| 53 | +- `MatrixForm(P)` returns a matrix representation of `P` as an upper triangular Toeplitz matrix |
| 54 | +- `reciprocal` computes the series reciprocal |
| 55 | +- `derivative` computes the series derivative |
| 56 | +- `isconstant(P)` determines if `P` is a constant series |
| 57 | +- `compose(P,Q)` computes the series composition P.Q |
| 58 | +- `isalmostunit(P)` determines if `P` is an almost unit series |
| 59 | + |
| 60 | +# Densities |
| 61 | + |
| 62 | +Famous distributions in random matrix theory |
| 63 | + |
| 64 | +- `Semicircle` provides the semicircle distribution |
| 65 | +- `TracyWidom` computes the Tracy-Widom density distribution by brute-force integration of the Painlevé II equation |
| 66 | + |
| 67 | +# Utility functions |
| 68 | + |
| 69 | +- `hist_eig` computes the histogram of eigenvalues of a matrix using the method of Sturm sequences. |
| 70 | + For `SymTridiagonal` matrices this is significantly faster than `hist(eigvals())` |
| 71 | + |
| 72 | +# References |
| 73 | +- James Albrecht, Cy Chan, and Alan Edelman, "Sturm Sequences and Random Eigenvalue Distributions", *Foundations of Computational Mathematics*, vol. 9 iss. 4 (2009), pp 461-483. [[pdf]](www-math.mit.edu/~edelman/homepage/papers/sturm.pdf) [[doi]](http://dx.doi.org/10.1007/s10208-008-9037-x) |
| 74 | +- Alan Edelman and Brian D. Sutton, "The beta-Jacobi matrix model, the CS decomposition, and generalized singular value problems", *Foundations of Computational Mathematics*, vol. 8 iss. 2 (2008), pp 259-285. [[pdf]](http://www-math.mit.edu/~edelman/homepage/papers/betajacobi.pdf) [[doi]](http://dx.doi.org/10.1007/s10208-006-0215-9) |
| 75 | +- Peter Henrici, *Applied and Computational Complex Analysis, Volume I: Power Series---Integration---Conformal Mapping---Location of Zeros*, Wiley-Interscience: New York, 1974 |
| 76 | + |
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