is a nonnegative integer
that represents the total number of elements from which the sample
is chosen.

r

is a nonnegative integer
that represents the number of chosen elements.

Restriction

r ≤ n

Details

The mathematical representation
of the COMB function is given by the following equation:

In the preceding equation, n ≥ 0, r ≥ 0, and n≥ r.

If the expression cannot
be computed, a missing value is returned. For moderately large values,
it is sometimes not possible to compute the COMB function.