Dirichlet function

The Dirichlet Distribution

Functions to compute the density of a Dirichlet distribution and to generate random realizations from such a distribution.

dDirichlet (x, alpha, log=FALSE)
rDirichlet (n, alpha)

Arguments

• alpha: Shape parameter vector.
• x: Vector of the same length as alpha.
• n: Number of realizations (vectors) to generate.
• log: Logical value. TRUE if computing the log density. Default is FALSE.

Returns

rDirichlet returns a vector of the same length as alpha if n=1, or a matrix with each row being an independent realization otherwise.

Author(s)

Audrey Q. Fu coded dDirichlet.

The code for rDirichlet is taken from a similar function in R package gregmisc by Gregory R. Warnes. His code was based on code posted by Ben Bolker to R-News on 15 Dec 2000. See documentation in gregmisc for further information.

Examples

x <- rDirichlet (5, rep (0.5, 3))
dDirichlet (x[1, ], rep (0.5, 3))