corSmooth: Smooth a Non PD Correlation Matrix

In fungible: Psychometric Functions from the Waller Lab

Smooth a Non PD Correlation Matrix

Description

A function for smoothing a non-positive definite correlation matrix by the method of Knol and Berger (1991).

Usage

corSmooth(R, eps = 1e+08 * .Machine$double.eps)

Arguments

R	A non-positive definite correlation matrix.
eps	Small positive number to control the size of the non-scaled smallest eigenvalue of the smoothed R matrix. Default = 1E8 * .Machine$double.eps

Value

Rsmoothed

A Smoothed (positive definite) correlation matrix.

Author(s)

Niels Waller

References

Knol, D. L., and Berger, M. P. F., (1991). Empirical comparison between factor analysis and multidimensional item response models.Multivariate Behavioral Research, 26, 457-477.

Examples

## choose eigenvalues such that R is NPD
l <- c(3.0749126,  0.9328397,  0.5523868,  0.4408609, -0.0010000)

## Generate NPD R
R <- genCorr(eigenval = l, seed = 123)
print(eigen(R)$values)

#> [1]  3.0749126  0.9328397  0.5523868  0.4408609 -0.0010000

## Smooth R
Rsm<-corSmooth(R, eps = 1E8 * .Machine$double.eps)
print(eigen(Rsm)$values)

#> [1] 3.074184e+00 9.326669e-01 5.523345e-01 4.408146e-01 2.219607e-08

fungible documentation built on May 29, 2024, 8:28 a.m.