hd_add {hyperdirichlet} | R Documentation

## Add two hyperdirichlet distributions

### Description

Given two hyperdirichlet distributions, “add” them, in the sense of concatenating their information, assumed to be independent.

### Usage

    hd_add(e1, e2, assume_validated = FALSE)

### Arguments

`e1,e2` | Hyperdirichlet distributions of the same dimension
`assume_validated` | Boolean, with default `FALSE` meaning that the returned sum cannot be assumed to be proper; so the returned hyperdirichlet object is tested with `is.proper()` (which is time-consuming). Set to `TRUE` only when you know that the sum is proper

### Details

Think of this function as a computerized embodiment of Bayes's theorem with `e1` representing the prior and `e2` representing one or more informative trials.

The basic guts of the function is `hyperdirichlet(powers(e1) + params(e2))`. Note that this is equivalent to `hyperdirichlet(params(e1) + powers(e2))`.

The functional form is not really intended for the end user; use `e1 + e2` instead (but observe that the sum will be validated using `is.proper()`, which may take a long time).

### Value

Returns a hyperdirichlet distribution

### Author(s)

Robin K. S. Hankin

### See Also

`hyperdirichlet`,`is.proper`,`Arith`

### Examples

    dirichlet(1:4) + gd(c(0.1 , 0.3 , 0.5), c(0.2 , 0.4 , 0.9))

    uniform(4) + single_bernoulli_obs(4,1,2)

    data(chess)
    ch <- as.hyperdirichlet(chess)
    stopifnot(all(params(ch+ch+ch) == params(ch*3)))

[Package hyperdirichlet version 1.3-8 Index]