R/iago.R

In exoplanetX/greyforecasting: A package for grey systems forecasting methods

#' IAGO operator
#'
#' Inverse accumulation operating generation
#' @export
#' @param x sequential data
#' @param r order of accumulation operating generation.

iago<-function(x,r=1){
  n=length(x)
  A=matrix(0,nrow=n,ncol=n)
  for(i in 1:n){
    for(j in 1:n){
      if(i==j)  A[i,j]=1
      if(i>j) A[i,j]=choose(i-j+r-1,i-j)
    }
  }
  r=as.vector(solve(A)%*%x)
  return(r)
}