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robcp (version 0.3.8)

modifChol: Revised Modified Cholesky Factorization

Description

Computes the revised modified Cholesky factorization described in Schnabel and Eskow (1999).

Usage

modifChol(x, tau = .Machine$double.eps^(1 / 3), 
           tau_bar = .Machine$double.eps^(2 / 3), mu = 0.1)

Value

Upper triangular matrix \(L\) of the form \(L'L = x + E\).

Arguments

x

a symmetric matrix.

tau

(machine epsilon)^(1/3).

tau_bar

(machine epsilon^(2/3)).

mu

numeric, \(0 < \mu \le 1\).

Author

Sheila Görz

Details

modif.chol computes the revised modified Cholesky Factorization of a symmetric, not necessarily positive definite matrix x + E such that \(L'L = x + E\) for \(E \ge 0\).

References

Schnabel, R. B., & Eskow, E. (1999). "A revised modified Cholesky factorization algorithm" SIAM Journal on optimization, 9(4), 1135-1148.

Examples

Run this code
y <- matrix(runif(9), ncol = 3)
x <- psi(y)
modifChol(lrv(x))

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