qgeneric function

Generic function to find quantiles of a distribution

Computes quantiles.

qgeneric(pdist, p, ...)

Details

For internal use

Note

Taken from msm R-package.

Examples

## The function is currently defined as
function(pdist, p, ...) {
  args <- list(...)
  if (is.null(args$log.p)) {
    args$log.p <- FALSE
  }
  if (is.null(args$lower.tail)) {
    args$lower.tail <- TRUE
  }
  if (is.null(args$lbound)) {
    args$lbound <- -Inf
  }
  if (is.null(args$ubound)) {
    args$ubound <- Inf
  }
  if (args$log.p) {
    p <- exp(p)
  }
  if (!args$lower.tail) {
    p <- 1 - p
  }
  ret <- numeric(length(p))
  ret[p == 0] <- args$lbound
  ret[p == 1] <- args$ubound
  args[c("lower.tail", "log.p", "lbound", "ubound")] <- NULL
  maxlen <- max(sapply(c(args, p = list(p)), length))
  for (i in seq(along = args)) {
    args[[i]] <- rep(args[[i]],
      length.out = maxlen
    )
  }
  p <- rep(p, length.out = maxlen)
  ret[p < 0 | p > 1] <- NaN
  ind <- (p > 0 & p < 1)
  if (any(ind)) {
    hind <- seq(along = p)[ind]
    h <- function(y) {
      args <- lapply(args, function(x) x[hind[i]])
      p <- p[hind[i]]
      args$q <- y
      (do.call(pdist, args) - p)
    }
    ptmp <- numeric(length(p[ind]))
    for (i in 1:length(p[ind])) {
      interval <- c(-1, 1)
      while (h(interval[1]) * h(interval[2]) >= 0) {
        interval <- interval + c(-1, 1) * 0.5 * (interval[2] -
          interval[1])
      }
      ptmp[i] <- uniroot(h, interval, tol = .Machine$double.eps)$root
    }
    ret[ind] <- ptmp
  }
  if (any(is.nan(ret))) {
    warning("NaNs produced")
  }
  ret
}

Author(s)

Christopher Jackson