Hello, I know that i have to use optim, but i'm confused how its possible maximize the sum over all l[i] and get the optimized r and alpha? LL <- function(trans,time){ for(i in 1:length(trans){ l[i] <- log(lgamma(r+trans[i] - gamma(r+1)*(alpha/alpha+t[i]))**r)*(t[i]/alpha+t[i])**trans[i] } return(sum(l)) } i'm confused how i have to set r and alpha and i found no related help in archives? ...in Excel it works with solver but only for ~65.000 rows :-) #This notation is 1 for trans and 1 for time insteda the Startvalues for r and alpha? optim(c(1,1),-LL) many thanks for an easy example or hint regards,christian