R: Fast calculation of the spherical and hyperspherical median

Spherical and hyperspherical median {Rfast} | R Documentation

## Fast calculation of the spherical and hyperspherical median

### Description

It calculates, very fast, the (hyper-)spherical median of a sample.

### Usage

    mediandir(x)

### Arguments

`x` | The data, a numeric matrix with unit vectors.

### Details

The "mediandir" employes a fixed poit iterative algorithm stemming from the first derivative (Cabrera and Watson, 1990) to find the median direction as described in Fisher (1985) and Fisher, Lewis and Embleton (1987).

### Value

The median direction.

### Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <mtsagris@uoc.gr>

### References

Fisher N. I. (1985). Spherical medians. Journal of the Royal Statistical Society. Series B, 47(2): 342-348.

Fisher N. I., Lewis T. and Embleton B. J. (1987). Statistical analysis of spherical data. Cambridge university press.

Cabrera J. and Watson G. S. (1990). On a spherical median related distribution. Communications in Statistics-Theory and Methods, 19(6): 1973-1986.

### See Also

`vmf.mle`

### Examples

    m <- rnorm(3)
    m <- m / sqrt( sum(m^2) )
    x <- rvmf(100, m, 10)
    res<-mediandir(x)
    x <- NULL

[Package Rfast version 2.0.4 Index]