Talk:Factorial
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An imperative way of calculating factorial may be more understandable. In Python code:
def fact(x):
result = 1
while x > 1:
result *= x # multiply result by x
x -= 1 # decrease x by 1
return result
Moved from the article. Is this really worth mention? -- Taku 21:38 Apr 25, 2003 (UTC)
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Derivative of the factorial
Does anyone know some values of the function that can be recieved by differentiating the factorial, using the ? symbol for this function?? A graphing calculator can be helpful. Try to see if you know the values of:
- 1? =
- 2? =
- 3? =
- 4? =
- 5? =
- 6? =
- 7? =
- 8? =
- 9? =
- 10? =
Dou you see a pattern for the values of n? for the integers?? (Look! We now have a mathematical meaning for just about every symbol on the computer; any counterexamples??)
- How can you differentiate the factorial when it isn't a continuous function? You could differentiate the gamma function, though. Eric119 22:41, Jun 30, 2004 (UTC)
Wouldn't it be better to mention the integral definition
- <math>z!=\int_{0}^{\infty} e^{-t}t^{z+1}\, dt<math>
in the discussion of the gamma function? 4pq1injbok 02:32, 16 Jul 2004 (UTC)
- No, it has obvious relevance here also. Dysprosia 02:38, 16 Jul 2004 (UTC)
- Sure, but isn't it still primarily about the gamma function? After all, the factorial is discrete, so defining it for nonintegral arguments is essentially defining the gamma function. It seems a bit scattered to me to talk about nonintegral z in two distinct places. 4pq1injbok 21:27, 16 Jul 2004 (UTC)
Is there a term for the sum of positive integers less than or equal to the given number? Bless me if I can't find reference to one.
Yes, a triangular number. --- User:Karl Palmen 5 August 2004
Adding an external link: http://www.luschny.de/math/factorial/FastFactorialFunctions.htm This site shows several interesting algorithms to compute the factorial.
Incorrect reference to "the above recursive relation"
"Proper attention to the value of the empty product is important in this case, because <...> it makes the above recursive relation work for n = 1;"
But the recursive relation is given at the end of the next section (Applications), not above.
Superfactorials
Superfactorials get large very rapidly. Between what two consecutive superfactorials does Graham's number lie?? 1$ = 1 and 2$ = 4, but even 3$ is too big to write; it is 6^6^6^6^6^6. 66.32.244.149 21:43, 2 Nov 2004 (UTC)
factorials for halves?
How does one calculate factorials that are in the form (n + .5)!, where n is a whole number? On windows calculator, it says 3.5! = 11.631728396567448929144224109426. how is this calculated?
- With the gamma function. Fredrik | talk 02:59, 9 Feb 2005 (UTC)
- Yup, 3.5! is the same as Γ(4.5). --MarkSweep 06:19, 9 Feb 2005 (UTC)