Talk:Gamma function: Difference between revisions

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imported>Aleksander Stos
(→‎On definition: extended)
imported>Fredrik Johansson
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I reworked slightly the definition, as it was not clear to me when ''z'' is taken to be real and when complex. Also, perhaps it is better to avoid uniform convergence at this point (isn't it more delicate?), just give continuity for granted as it is done when we say that the function is analytic. I did not understood either _why_we use for Re(z)<0 the functional equation that was "justified"  for Re(z)>0. In fact, I guess that we make a formal definition which coincides with the formerly introduced analytic continuation.--[[User:Aleksander Stos|AlekStos]] 09:00, 11 April 2007 (CDT)
I reworked slightly the definition, as it was not clear to me when ''z'' is taken to be real and when complex. Also, perhaps it is better to avoid uniform convergence at this point (isn't it more delicate?), just give continuity for granted as it is done when we say that the function is analytic. I did not understood either _why_we use for Re(z)<0 the functional equation that was "justified"  for Re(z)>0. In fact, I guess that we make a formal definition which coincides with the formerly introduced analytic continuation.--[[User:Aleksander Stos|AlekStos]] 09:00, 11 April 2007 (CDT)
:I like your change. The functional-equation formula can be taken as the definition of the gamma function of a negative number. I've no idea what it'd take to prove that it really is the analytic continuation (or whatever else is needed), but I think a rigorous derivation would probably be too technical for this article. The presentation roughly follows that given in the appendix on the gamma function in Folland, ''Fourier analysis and its applications'', which I found very readable. [[User:Fredrik Johansson|Fredrik Johansson]] 09:39, 11 April 2007 (CDT)

Revision as of 09:39, 11 April 2007


Article Checklist for "Gamma function"
Workgroup category or categories Mathematics Workgroup [Categories OK]
Article status Developed article: complete or nearly so
Underlinked article? Yes
Basic cleanup done? Yes
Checklist last edited by --AlekStos 03:50, 11 April 2007 (CDT)

To learn how to fill out this checklist, please see CZ:The Article Checklist.





On definition

I reworked slightly the definition, as it was not clear to me when z is taken to be real and when complex. Also, perhaps it is better to avoid uniform convergence at this point (isn't it more delicate?), just give continuity for granted as it is done when we say that the function is analytic. I did not understood either _why_we use for Re(z)<0 the functional equation that was "justified" for Re(z)>0. In fact, I guess that we make a formal definition which coincides with the formerly introduced analytic continuation.--AlekStos 09:00, 11 April 2007 (CDT)

I like your change. The functional-equation formula can be taken as the definition of the gamma function of a negative number. I've no idea what it'd take to prove that it really is the analytic continuation (or whatever else is needed), but I think a rigorous derivation would probably be too technical for this article. The presentation roughly follows that given in the appendix on the gamma function in Folland, Fourier analysis and its applications, which I found very readable. Fredrik Johansson 09:39, 11 April 2007 (CDT)