vmises.kappa: Circular variance and concentration parameter
Description
Return the concentration parameter that corresponds to a given circular
variance.
Usage
vmises.kappa(nu)
Value
Concentration parameter corresponding to nu.
Arguments
nu
circular variance
Details
The concentration parameter \(\kappa\) does not translate across circular
distributions. A commonly used measure of spread in circular distributions
that does translate is the circular variance defined as
\(\nu=1-E[\cos(r)]\) where \(E[\cos(r)]\) is
the mean resultant length. See mardia2000 for more details. This
function translates the circular variance \(\nu\) into the corresponding
concentration parameter \(\kappa\) for the circular-von Mises
distribution. For numerical stability, a maximum \(\kappa\) of 500 is
returned.