Hello Friends, I am trying to use the functions ksdrift and ksdiff both in SDE package. Unfortunately. It does not work for my data (attached). The following code shows how I tried to use it: setwd("D:/Mohammad/Different/New folder") mydata <- read.csv("Best.csv", header=FALSE) myts<-ts(mydata,start=c(0, 1), end=c(523, 1), frequency=1) X<-myts set.seed(123) theta <- c(-2026651,-146668.995,-3531.84,-28.3,-46740,-2238,-26.57) b <- function(x) theta[1]+theta[2]*x+theta[3]*x^2+theta[4]*x^3 sigma <- function(x) theta[5]+theta[6]*x+theta[7]*x^2 minX <- min(X) maxX <- max(X) par(mfrow=c(2,1)) curve(b,minX, maxX) lines(ksdrift(X)) curve(sigma,minX, maxX) lines(ksdiff(X)) Although I do not get any error message I do not get any solution to my problem. I would be very grateful if any of you can help me on this. Kind regards, Babak, Wageningen University