multinomial {MM}

Multinomial function

Description

The multinomial function and its logarithm

Usage

multinomial(x)
lmultinomial(x)

Arguments

x

Numeric vector

Details

Function multinomial() returns

\[{n\choose n_1,n_2,\ldots,n_k} = \frac{n!}{n_1!n_2!\cdots n_k!}\]

where \(\sum_i n_i=n\), and function lmultinomial() returns the natural logarithm of this.

Note

Uses logarithmic functions to avoid overflow.

Author(s)

Robin K. S. Hankin

Examples

x <- runif(10)

exp(lmultinomial(x)) - multinomial(x) #should be small