Hello,
I'd like to obtain parameters for my poisson data. Having made the function

poisregfun = function(a,b) {Y.pred = exp(a + b*x) - sum(dpois(y, lambda =
Y.pred, log = TRUE))}

where Y is a vector of data to be regressed on another vector x.
I'm asking for

mle2(  poisregfun, start = list(a = 21, b = 0.7),
method = "Nelder-Mead")

Do I need more arguments than this?
regards,
Russell
(computer replies with:
'Error in optim(par = c(21, 0.7), fn = function (p)  :
  objective function in optim evaluates to length 20 not 1')

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