R: Simplex Distribution

Simplex {VGAM} | R Documentation

## Simplex Distribution

### Description

Density function, and random generation for the simplex distribution.

### Usage

    dsimplex(x, mu = 0.5, dispersion = 1, log = FALSE)
    rsimplex(n, mu = 0.5, dispersion = 1)

### Arguments

`x` | Vector of quantiles. The support of the distribution is the interval (0,1).
`mu, dispersion` | Mean and dispersion parameters. The former lies in the interval (0,1) and the latter is positive.
`n, log` | Same usage as `runif`.

### Details

The VGAM family function `simplex` fits this model; see that online help for more information. For `rsimplex()` the rejection method is used; it may be very slow if the density is highly peaked, and will fail if the density asymptotes at the boundary.

### Value

`dsimplex(x)` gives the density function, `rsimplex(n)` gives n random variates.

### Author(s)

T. W. Yee

### See Also

`simplex`.

### Examples

    sigma <- c(4, 2, 1)  # Dispersion parameter
    mymu  <- c(0.1, 0.5, 0.7); xxx <- seq(0, 1, len = 501)
    ## Not run:  par(mfrow = c(3, 3))  # Figure 2.1 of Song (2007)
    for (iii in 1:3)
      for (jjj in 1:3) {
        plot(xxx, dsimplex(xxx, mymu[jjj], sigma[iii]),
             type = "l", col = "blue", xlab = "", ylab = "", main =
             paste("mu = ", mymu[jjj], ", sigma = ", sigma[iii], sep = "")) }
    ## End(Not run)

[Package VGAM version 1.0-3 Index]