+0

# decimal FACTORIALS

0
267
3
+271

How do we calculate the factorial of a decimal? :-?

Pyramid  Apr 7, 2015

#3
+91469
+10

Mmm   Thanks Pyramid, that is a really good question.  One that I will have problems answering but here goes :)

If you graph y=x!    (where x is a integer greater or equal to zero) you get a graph of points.

If you draw a smooth curve between these points so that the graph is continuous then you will have all positive values of x (x>=1) and all values of y (y>=1) included.

So now you can read 2.4! off the graph.

The gamma functions has values outside this domain as well but i don't understand it well enough to explain those.

I don't think my explanation is very accurate.  But it probably gives you as much of an idea as I possess. :)

There is of course a proper formula for n! where n is not an integer but I am not going there. :/

http://en.wikipedia.org/wiki/Gamma_function

Any better explanation will be gratefully received.   :)

Melody  Apr 7, 2015
Sort:

#1
+17711
+5

Use gamma functions. This site http://mhtlab.uwaterloo.ca/courses/me755/web_chap1.pdf has an explanation, starting on page 7.

geno3141  Apr 7, 2015
#2
+271
+5

What does it really mean?

Pyramid  Apr 7, 2015
#3
+91469
+10

Mmm   Thanks Pyramid, that is a really good question.  One that I will have problems answering but here goes :)

If you graph y=x!    (where x is a integer greater or equal to zero) you get a graph of points.

If you draw a smooth curve between these points so that the graph is continuous then you will have all positive values of x (x>=1) and all values of y (y>=1) included.

So now you can read 2.4! off the graph.

The gamma functions has values outside this domain as well but i don't understand it well enough to explain those.

I don't think my explanation is very accurate.  But it probably gives you as much of an idea as I possess. :)

There is of course a proper formula for n! where n is not an integer but I am not going there. :/

http://en.wikipedia.org/wiki/Gamma_function

Any better explanation will be gratefully received.   :)

Melody  Apr 7, 2015

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