qbinom returns NaN

Hi, All:

	  For most but not all cases, qbinom is the inverse of pbinom.
Consider the following example, which generates an exception:

(pb01 <- pbinom(0:1, 1, .5, log=T, lower.tail=FALSE))

[1] -0.6931472       -Inf

	  Since "lower.tail=FALSE", Pr{X>1} = 0 in this context, and log(0) =
-Inf, consistent with the documentation.

	  However, the inverse of this does NOT recover 0:1:

qbinom(pb01,1, .5, log=T, lower.tail=F)

[1]   0 NaN

	  Shouldn't the NaN here be 1?  If yes, this is relatively easy to fix.
 Consider for example the following:

qbinom. <-
function (p, size, prob, lower.tail = TRUE, log.p = FALSE){
  q. <- .Internal(qbinom(p, size, prob, lower.tail, log.p))
  q.[p==(-Inf)] <- 1
  q.
}

qbinom.(pb01,1, .5, log=T, lower.tail=F)

[1] 0 1
Warning message:
NaNs produced in: qbinom(p, size, prob, lower.tail, log.p)

	  It's also easy to eliminate the Warning.  Consider for example the
following:

qbinom. <-
function (p, size, prob, lower.tail = TRUE, log.p = FALSE){
  if(any(p.inf <- p==(-Inf))&&(!lower.tail)&&log.p){
    n <- max(length(p), length(size), length(prob))
    p <- rep(p, length=n)
    size <- rep(size, length=n)
    prob <- rep(prob, length=n)
    q. <- size
    q.[p>(-Inf)] <- .Internal(qbinom(p[!p.inf],
            size[!p.inf], prob[!p.inf], lower.tail, log.p))
    return(q.)
  }
  .Internal(qbinom(p, size, prob, lower.tail, log.p))
}

	  I suspect that for the right person, it would likely be easy to fix
this in the .Internal qbinom code.  However, that's beyond my current R
skill level.

	  Thanks for all your efforts to make R what it is today.
	  Best Wishes,
	  spencer graves

-- 
Spencer Graves, PhD
Senior Development Engineer
PDF Solutions, Inc.
333 West San Carlos Street Suite 700
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