fisher.kappa {rotations} | R Documentation |
Return the concentration parameter that corresponds to a given circular variance.
fisher.kappa(nu)
nu |
circular variance |
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 matrix-Fisher distribution.
For numerical stability, a maximum \kappa
of 350 is returned.
mardia2000
Concentration parameter corresponding to nu.
# 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)