% File src/library/base/man/diff.Rd % Part of the R package, http://www.R-project.org % Copyright 1995-2011 R Core Team % Distributed under GPL 2 or later \name{diff} \alias{diff} \alias{diff.default} \alias{diff.POSIXt} \alias{diff.Date} \concept{difference} \title{Lagged Differences} \description{ Returns suitably lagged and iterated differences. } \usage{ diff(x, \dots) \method{diff}{default}(x, lag = 1, differences = 1, \dots) \method{diff}{POSIXt}(x, lag = 1, differences = 1, \dots) \method{diff}{Date}(x, lag = 1, differences = 1, \dots) } \arguments{ \item{x}{a numeric vector or matrix containing the values to be differenced.} \item{lag}{an integer indicating which lag to use.} \item{differences}{an integer indicating the order of the difference.} \item{\dots}{further arguments to be passed to or from methods.} } \details{ \code{diff} is a generic function with a default method and ones for classes \code{"\link{ts}"}, \code{"\link{POSIXt}"} and \code{"\link{Date}"}. \code{\link{NA}}'s propagate. } \value{ If \code{x} is a vector of length \code{n} and \code{differences=1}, then the computed result is equal to the successive differences \code{x[(1+lag):n] - x[1:(n-lag)]}. If \code{difference} is larger than one this algorithm is applied recursively to \code{x}. Note that the returned value is a vector which is shorter than \code{x}. If \code{x} is a matrix then the difference operations are carried out on each column separately. } \references{ Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) \emph{The New S Language}. Wadsworth & Brooks/Cole. } \seealso{ \code{\link{diff.ts}}, \code{\link{diffinv}}. } \examples{ diff(1:10, 2) diff(1:10, 2, 2) x <- cumsum(cumsum(1:10)) diff(x, lag = 2) diff(x, differences = 2) diff(.leap.seconds) } \keyword{arith}