[net.math] derivative of x!

kvanston@muddcs.UUCP (Kathryn Vanstone) (05/10/85)

*** REPLACE THIS LINE WITH YOUR REBUTTAL ***
>It appears that the gamma function is unknown to this mathematician. To 
>derive the gamma function from the usual multiplicative definition on
>the integers, use the Euler product. It is not hard to show that the
>gamma function is analytic on a real segment, and then by analytic
>continuation to the complex plane with negative integral points deleted.
>If one would like to stick to the integers, one can be made to look 
>unnaturally restricted, since the complex field is determined by the ring of 
>integers ... it is the algebraic closure of the completion of the field of
>fractions of the ring of integers.           


Of course I know about the Gamma function! (i'd better...I've just taken
a test in Bessel functions).  So did the people in net.puzzle.  The Gamma
function is differentiable everywhere (on the reals) except the non-positive
integers.  However, several people in net.puzzle claimed that x! was not
continuous when defined on the integers, and I wanted to point out that
that statement is false.  The discussion on the derivative of the Gamma
function did not need comment.

So I wasn't so much commenting on the answer (except to state that I would
request a definition of the space that x! was defined over), but on the
discussion of the answer.

I probably should have included a copy of some of the discussions, but
I haven't got the hang of this net yet.

					Kathryn Van Stone

					Harvey Mudd College

<Oh, well, I don't remember this part...>
"Led go by dose, your hurdig be!"