R Under development (unstable) (2023-12-07 r85661 ucrt) -- "Unsuffered Consequences"
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> library(bbmle)
Loading required package: stats4
> x <- 0:10
> y <- c(26, 17, 13, 12, 20, 5, 9, 8, 5, 4, 8)
> d <- data.frame(x,y)
> 
> ## uses default parameters of LL
> fit <- mle2(y~dpois(exp(loglam)),
+             data=d,
+            start=list(loglam=0),control=list(maxit=2))
Warning message:
In mle2(y ~ dpois(exp(loglam)), data = d, start = list(loglam = 0),  :
  convergence failure: code=1 (iteration limit 'maxit' reached)
> pp <- profile(fit)
Profiling has found a better solution,so original fit had not converged:

(new deviance=252, old deviance=272.7, diff=-20.78)

Returning better fit ...

> 
> proc.time()
   user  system elapsed 
   1.65    0.12    1.75