underflow of fisher.test result

On 20-Oct-09 13:34:49, Peng Yu wrote:

fisher.test() gives a very small p-value, which is underflow on my
machine. However, the log of it should not be underflow. I'm wondering
if there is a way get log() of a small p-value. An approximation is
acceptable in this case. Thank you!

fisher.test(rbind(c(10000,100000),c(100000,10000000)))$p.value

[1] 0

I have not attempted an exact approach (though may do so later),
but the P-value in question is about 1e-15000 so (using log to
base e)

?log(P) approx = -33000

In such a case, P=0 is a pretty good approximation!

Which prompts the question: Why the interest in having the value
of such a very small number?