#  File src/library/stats/R/ppoints.R
#  Part of the R package, https://www.R-project.org
#
#  Copyright (C) 1995-2016 The R Core Team
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  A copy of the GNU General Public License is available at
#  https://www.R-project.org/Licenses/

ppoints <- function (n, a = if(n <= 10) 3/8 else 1/2)
{
    if(length(n) > 1L) n <- length(n)
    if(n > 0) (1L:n - a)/(n + 1-2*a) else numeric()
}