R Under development (unstable) (2023-12-07 r85661 ucrt) -- "Unsuffered Consequences"
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> library(bbmle)
Loading required package: stats4
> set.seed(1001)
> f <- factor(rep(1:3,each=50))
> kvals <- c(1,2,5)
> muvals <- c(10,2,5)
> y <- rnbinom(length(f),size=kvals[f],mu=muvals[f])
> plot(y)
> 
> NLL <- function(p) {
+   kvals <- p[1:3]
+   muvals <- p[4:6]
+   -sum(dnbinom(y,size=kvals[f],mu=muvals[f],log=TRUE))
+ }
> parnames(NLL) <- c("k1","k2","k3","mu1","mu2","mu3")
> svec <- c(kvals,muvals)
> names(svec) <- parnames(NLL)
> m1 <- mle2(NLL,start=svec,vecpar=TRUE)
> 
> proc.time()
   user  system elapsed 
   1.40    0.09    1.48