R/PV_pre_exact.R

In AnnuityRIR: Annuity Random Interest Rates

# from moments package

moment=function (x, order = 1, central = FALSE, absolute = FALSE, na.rm = FALSE)
{
  if (is.matrix(x))
    apply(x, 2, moment, order = order, central = central,
          absolute = absolute, na.rm = na.rm)
  else if (is.vector(x)) {
    if (na.rm)
      x = x[!is.na(x)]
    if (central)
      x = x - mean(x)
    if (absolute)
      x = abs(x)
    sum(x^order)/length(x)
  }
  else if (is.data.frame(x))
    sapply(x, moment, order = order, central = central, absolute = absolute,
           na.rm = na.rm)
  else moment(as.vector(x), order = order, central = central,
              absolute = absolute, na.rm = na.rm)
}


PV_pre_exact=function(data,years=10){

X=data
U=1+X
n=years
a=rep(NA,n)
for (i in 1:n) a[i]=moment(U, central = FALSE, absolute = FALSE, order =-i)
PV=sum(a[1:n-1])+1
return(PV)
}