- * objects from n distinct objects. If n is negative, the formula
- * binomial(n,k) == (-1)^k*binomial(k-n-1,k) is used to compute the result. */
+ * objects from n distinct objects. If n is a negative integer, the formula
+ * binomial(n,k) == (-1)^k*binomial(k-n-1,k) (if k>=0)
+ * binomial(n,k) == (-1)^(n-k)*binomial(-k-1,n-k) (otherwise)
+ * is used to compute the result. */