[R] how to compute the inverse percentile of a given observation w.r.t. a reference distribution

[rudi]

Hi,

can anyone help me to figure out how to compute the percentile of an
individual observation with respect to a reference distribution.

What I mean is. Let's assume I have a vector consisting of 10 numbers
{3,5,8,1,9,5,4,3,5.5,7} and I want figure out what percentile the
number 4.9 corresponds to. I failed to find any reference to such a
function, although I would assume this must frequently be necessary.

Thanks in advance for you help.

/Rudi