fisher.kappa: Circular variance and concentration parameter

In rotations: Working with Rotation Data

Circular variance and concentration parameter

Description

Return the concentration parameter that corresponds to a given circular variance.

Usage

fisher.kappa(nu)

Arguments

nu	circular variance

Details

The concentration parameter κ does not translate across circular distributions. A commonly used measure of spread in circular distributions that does translate is the circular variance defined as ν=1-E[cos(r)] where E[cos(r)] is the mean resultant length. See mardia2000 for more details. This function translates the circular variance ν into the corresponding concentration parameter κ for the matrix-Fisher distribution. For numerical stability, a maximum κ of 350 is returned.

mardia2000

Value

Concentration parameter corresponding to nu.

See Also

Fisher

Examples

# Find the concentration parameter for circular variances 0.25, 0.5, 0.75
fisher.kappa(0.25)
fisher.kappa(0.5)
fisher.kappa(0.75)

rotations documentation built on June 25, 2022, 1:06 a.m.