Factorial Calculation Using Stirlings Formula
Calculator find the Factorial n for given Number of elements.
Calculator is using Stirling's formula gives an approximate value for the factorial function n! for n < 0.
The factorial function n! is important in computing binomial, hypergeometric, and other probabilities.
If n is not too large, then n! can be computed directly, multiplying the integers from 1 to n, or person can look up factorials in some tables.
Stirling’s formula provides an approximation which is relatively easy to compute and is sufficient for most of the purposes.
Using n! ≈ √(2π) x n(n+1/2)x e -n
where n is number of elements.
Example
The factorial of n is represented by n!. The factorial of n means, we have to multiply all the whole numbers from n down to 1.
The factorial of 5 is calculated as follows:
Factorial of 5 (5!) = 5 x 4 x 3 x 2 x 1.
Factorial of 5 = 118.
To Find: 5 factorial. Using Stirling Formula
n! ≈ √(2π) x n(n+1/2) x e -n
n! ≈ √(2xπ) x 5(5+1/2) x e -5
= 118.019