#' Control Chart Constant d3 / D3
#'
#' Calculate d3 or D3 control chart constant from Wheeler's SPC books. These are in the same help file
#' because of a quirk of how R generates help file names, but they are different constants with different uses.
#'
#' @param sample.size A scalar or vector of sample sizes
#' @param n.sigma Scalar - How many standard errors to use (default 3 for most control charts)
#' @param negative.as.NA Logical - negative values are possible from the calculation, but not useful. Set to false to obtain negative values instead of NA.
#'
#' @return A scalar or vector with computed constants.
spc.constant.calculation.D3 <- function(
sample.size,
n.sigma = 3,
negative.as.NA = T
) {
sapply(sample.size, FUN = function(i) {
ret <- 1 - n.sigma * spc.constant.calculation.d3(i) / spc.constant.calculation.d2(i)
if (ret < 0 & negative.as.NA) {
ret <- NA
}
ret
})
}
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