That is interesting, if is a little counterintuitive; it seems reasonable to speak of sampling from a normal distribution with standard deviation approaching or equal to zero. Yet, as you point out, this could lead to division by zero - at least using this formulation of the probability function.
Thanks for the reply and for the excellent pointer. Paul -----Original Message----- From: J.Pietschmann [mailto:[EMAIL PROTECTED] Sent: 08 August 2005 21:24 To: Jakarta Commons Users List Subject: Re: [math] RandomData: Zero variance in Gaussian distribution? Paul Doyle wrote: > The RandomData interface stipulates that the standard deviation value > for a call to nextGaussian(double mu, double sigma) should be greater > than zero. Can anybody explain to me why this restriction exists? It is a restriction of the distribution itself, rather than an implementation restriction. See http://mathworld.wolfram.com/GaussianFunction.html Given that the standard deviation is in the denominator of a subexpression in the distribution function, it seems unwise to allow a value of zero. J.Pietschmann This e-mail and any files transmitted with it are confidential and may be privileged and are intended solely for the individual named/ for the use of the individual or entity to whom they are addressed.If you are not the intended addressee, you should not disseminate, distribute or copy this e-mail.Please notify the sender immediately if you have received this e-mail by mistake and delete this e-mail from your system.If you are not the intended recipient, you are notified that reviewing, disclosing, copying, distributing or taking any action in reliance on the contents of this e-mail is strictly prohibited.Please note that any views or opinions expressed in this e-mail are solely those of the author and do not necessarily represent those of Traventec Limited. This e-mail has been swept for computer viruses however Traventec Limited accepts no liability for any damage caused by any virus transmitted by this e-mail.
