[Rd] pbinom( ) function (PR#8700)

[cspark at clemson.edu]

Full_Name: Chanseok Park
Version: R 2.2.1
OS: RedHat EL4
Submission from: (NULL) (130.127.112.89)



pbinom(any negative value, size, prob) should be zero. 
But I got the following results. 
I mean, if a negative value is close to zero, then pbinom() calculate
pbinom(0, size, prob). dbinom() also behaves similarly. 


> pbinom( -2.220446e-22, 3,.1)
[1] 0.729

> pbinom( -2.220446e-8, 3,.1)
[1] 0.729

> pbinom( -2.220446e-7, 3,.1)
[1] 0