Computes measures of dispersion for a directional data set.
circ.disp(x)vector of circular data measured in radians.
Returns a dataframe with the following components. The sample size, n; the resultant length, r; the mean resultant length, rbar= r/n; and the circular variance, var=(1-r/n).
Jammalamadaka, S. Rao and SenGupta, A. (2001). Topics in Circular Statistics, Section 1.3, World Scientific Press, Singapore.