p0: Centering function

In BNPdensity: Ferguson-Klass Type Algorithm for Posterior Normalized Random Measures

Centering function

Description

This function determines the centering density of the normalized random measure.

Usage

p0(x, distr = NULL, mu = NULL, sigma = NULL)

Details

For internal use.

Examples

## The function is currently defined as
function(x, distr = NULL, mu = NULL, sigma = NULL) {
  if (is.null(distr)) {
    stop("Argument \"distr\" should be defined numeric with possible values 1,2, or 3")
  }
  else if (distr == 1) {
    a <- ifelse(is.null(mu), 0, mu)
    b <- ifelse(is.null(sigma), 1, sigma)
    p0 <- dnorm(x, mean = a, sd = b)
  }
  else if (distr == 2) {
    a <- ifelse(is.null(mu), 1, mu^2 / sigma^2)
    b <- ifelse(is.null(sigma), 1, mu / sigma^2)
    p0 <- dgamma(x, shape = a, rate = b)
  }
  else if (distr == 3) {
    a <- ifelse(is.null(mu), 0.5, (1 - mu) * (mu / sigma)^2 -
      mu)
    b <- ifelse(is.null(sigma), 1 / sqrt(12), (mu * (1 - mu) / sigma^2 -
      1) * (1 - mu))
    if (any(c(a, b) <= 0)) {
      stop(paste(
        "\nNegative Beta parameters:\n a =", a,
        ";\t b =", b
      ))
    }
    p0 <- dbeta(x, shape1 = a, shape2 = b)
  }
  else {
    stop("Argument \"distr\" should be defined numeric with possible values 1,2, or 3")
  }
  return(p0)
}

BNPdensity documentation built on April 1, 2023, 12:10 a.m.