Actually, since NaN's are also detected in na.action operations, a
simpler fix
might just be to use the na.rm = TRUE option of min
upper <- min(n^k/(c^(k - 1)), 1, na.rm = TRUE)
> Recent news articles concerning an article from The Lancet with
> fabricated
> data indicate
> that in the sample containing some 900 or so patients, more than 200
> had
> the same
> birthday. I was curious and tried out the p and q birthday functions
> but
> pbirthday
> could not handle 250 coincidences with n = 1000. The calculation of
> upper
> prior
> to using uniroot produces NaN,
>
> upper<-min(n^k/(c^(k-1)),1)
>
> I was able to get it to work by using logs, however, as in the
> following
> version
>
> function(n, classes = 365, coincident = 2){
> k <- coincident
> c <- classes
> if (coincident < 2) return(1)
> if (coincident > n) return(0)
> if (n > classes * (coincident - 1)) return(1)
> eps <- 1e-14
> if (qbirthday(1 - eps, classes, coincident) <= n)
> return(1 - eps)
> f <- function(p) qbirthday(p, c, k) - n
> lower <- 0
> upper <- min( exp( k * log(n) - (k-1) * log(c) ), 1 )
> nmin <- uniroot(f, c(lower, upper), tol = eps)
> nmin$root
> }
[[alternative text/enriched version deleted]]
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