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Re: random numbers with gamma distribution [message #13420 is a reply to message #13416]

Wed, 04 November 1998 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

T.Osborn (f055@uea.ac.uk) writes:

> I'm trying to generate a random series that has a gamma distribution, using
> the randomu() function with the gamma keyword. The online help says to set
> gamma to an integer > 0. WHY DOES IT HAVE TO BE AN INTEGER? The gamma
> distribution is in fact defined for all gamma > 0, not just integers.
> I want to set gamma=0.5, which currently fails as it converts it to the
> integer 0, which is not > 0, and so it fails.
>
> Is this a bug, and is there any work-around?

Which gamma function are you running? Certainly not IDL's
GAMMA function which works perfectly well with non-integer
values:

IDL> print, gamma(0.5)
% Compiled module: GAMMA.
1.77245

Cheers,

David

----------------------------------------------------------
David Fanning, Ph.D.
Fanning Software Consulting
E-Mail: davidf@dfanning.com
Phone: 970-221-0438, Toll-Free Book Orders: 1-888-461-0155
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		Re: random numbers with gamma distribution By: Alejandro C. Frery on Mon, 09 November 1998 00:00
		Re: random numbers with gamma distribution By: davidf on Wed, 04 November 1998 00:00
		Re: random numbers with gamma distribution By: steinhh on Wed, 04 November 1998 00:00
		Re: random numbers with gamma distribution By: davidf on Wed, 04 November 1998 00:00

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