Define a function that takes a number as an argument, and returns the factorial for that number.

The exclamation point in the equation represents a factorial.

The general formula is , which grows even faster than an exponential function.

The exclamation point in the equation represents a factorial.

gamma function The gamma function of x is the generalization of the common factorial function n!.

In general, it can be shown that the factorial function grows even faster than exponentially.

Remember the factorial function we implemented previously?

This is similar to the factorial function we wrote earlier.

Let's walk through a simple example: the factorial function implemented in C.

The hyperfactorial function is similar to the factorial, but produces larger numbers.

The domain of the factorial function is the positive whole numbers.

In F#, the factorial function can be written concisely as follows:

Let’s develop the answer with an easier example of a recursive function, the factorial function:

The gamma function is related to the factorial function by the identity gamma(n + 1) = n! for integer n.

Γ(z) is the gamma function, a generalization of the factorial function to non-integer values.