Definition: For large values of n, n! ≈ (n/e)n √(2nπ).
See also factorial, gamma function.
Note: This approximation is taken directly from Stirling's formula.
Peter Luschny lists and evaluates many approximation formulas for n!. See Eric W. Weisstein, Stirling's Approximation for a derivation and other approximations. A slightly different approximation and relative errors from Bart j. Van Zeghbroeck's book.
If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.
Entry modified 4 May 2009.
HTML page formatted Tue Dec 6 16:16:32 2011.
Cite this as:
Paul E. Black, "Stirling's approximation", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed., U.S. National Institute of Standards and Technology. 4 May 2009. (accessed TODAY) Available from: http://www.nist.gov/dads/HTML/stirlingsApproximation.html