factorial
Factorial, Combinations, and Permutations
Description
Computes the factorial (n!), the binomial coefficients,
and the number of combinations.
Usage
factorial(x)
lfactorial(x)
choose(n, k)
lchoose(n, k)
Arguments
| x, n |
an integer vector.
Need not to be an integer for factorial
or lfactorial. |
| k |
an integer vector. |
| m |
an integer vector that sums to n. |
Details
These functions use gamma and lgamma for computations.
Value
returns a numeric vector. Specifically:
| factorial(x) |
returns x!. |
| lfactorial(x) |
returns the natural logarithm of x!. |
| choose(n, k) |
returns n! / (k! (n-k)!);
the number of ways of selecting k items from n when order does not matter.
|
| lchoose(n, k) |
returns the natural logarithm of n! / (k! (n-k)!). |
See Also
Examples
factorial(5:7)
lfactorial(5.5)
choose(5, 2)
lchoose(5.2, 2)
choose(5, -1:6)