"SD" <- function (x, na.rm = TRUE) { if (is.matrix(x)) apply(x, 2, SD, na.rm = na.rm) else if (is.vector(x)) sqrt(var(x, na.rm = na.rm,use="pair")) else if (is.data.frame(x)) apply(x,2, SD, na.rm = na.rm) else sqrt(var(as.vector(x), na.rm = na.rm,use="pair")) }