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Noise Sphere

• To: mathgroup at smc.vnet.net
• Subject: [mg25316] Noise Sphere
• From: Geoffrey Steeves <gsteeves at gpu.srv.ualberta.ca>
• Date: Tue, 19 Sep 2000 03:45:46 -0400 (EDT)
• Organization: University of Alberta
• Sender: owner-wri-mathgroup at wolfram.com

: In studying whether a sequence of numbers is random, one can construct
: what is called a Noise
: Sphere(http://mathworld.wolfram.com/NoiseSphere.html).  When I tried this
: out, I got a non-uniform distibution of points concentrated along
: the verticle axis (phi ~= 0) of the sphere.  Initially I thought that this
: was an artifact of my pseudo-random number generator, but I later tried
: this out with "real" random numbers and got the same distribution.
: Looking at the mapping(as it is shown on the web page):

: theta = 2 * Pi * Random[]

: phi = Pi * Random[]

: r = Sqrt[Random[]]

: I thought that the problem was with the distribution in phi.  Is this a
: mistake in the map?  Or am I misunderstanding the what a Noise spehere is
: supposed to be?  Thanks for the help!


: -- 
: ___________________________________________________________________________
:              Geoff Steeves // University of Alberta Physics //

: 			http://www.ualberta.ca/~gsteeves
: ---------------------------------------------------------------------------