Hi Josh I have run the code and the structure of the output is what I wanted. However, the code is giving an identical result for all runs.
I have attached the code I ran below as well as the output. I have just changed number of runs to match with the size of the data. a=read.table("D:/hope.txt",header=T) attach(a) a #likilihood function llik = function(x) { al_j=x[1]; au_j=x[2]; sigma_j=x[3]; b_j=x[4] sum(na.rm=T, ifelse(a$R_j< 0, -log(1/(2*pi*(sigma_j^2)))- (1/(2*(sigma_j^2))*(a$R_j+al_j-b_j*a$R_m))^2, ifelse(a$R_j>0 , -log(1/(2*pi*(sigma_j^2)))- (1/(2*(sigma_j^2))*(a$R_j+au_j-b_j*a$R_m))^2, -log(ifelse (( pnorm (au_j, mean=b_j * a$R_m, sd= sqrt(sigma_j^2))- pnorm(al_j, mean=b_j * a$R_m, sd=sqrt (sigma_j^2) )) > 0, (pnorm (au_j,mean=b_j * a$R_m, sd= sqrt(sigma_j^2))- pnorm(al_j, mean=b_j * a$R_m, sd= sqrt(sigma_j^2) )), 1)) )) ) } start.par = c(-0.01,0.01,0.1,1) #looping now runs=133/20+1 #total data points divided by number od days in each quater+1 out <- matrix(NA, nrow = runs, ncol = 4, dimnames = list(paste("Quater:", 1:runs, sep = ''), c("al_j", "au_j", "sigma_j", "b_j"))) for (i in 1:runs) { a[seq(20 * (i - 1) +1, 20 * i), ] out[i, ] <- optim(llik, par = start.par, method = "Nelder-Mead")[[1]] } out #results I am getting > out al_j au_j sigma_j b_j Quater:1 0.04001525 0.06006251 -7.171336e-25 1.049982 Quater:2 0.04001525 0.06006251 -7.171336e-25 1.049982 Quater:3 0.04001525 0.06006251 -7.171336e-25 1.049982 Quater:4 0.04001525 0.06006251 -7.171336e-25 1.049982 Quater:5 0.04001525 0.06006251 -7.171336e-25 1.049982 Quater:6 0.04001525 0.06006251 -7.171336e-25 1.049982 Quater:7 0.04001525 0.06006251 -7.171336e-25 1.049982 > -- View this message in context: http://r.789695.n4.nabble.com/loop-in-optim-tp3643230p3647549.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.