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MathGroup Archive 1998

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Re: creating distributions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg14741] Re: [mg14697] creating distributions
  • From: Jurgen Tischer <jtischer at col2.telecom.com.co>
  • Date: Wed, 11 Nov 1998 17:53:43 -0500
  • Organization: Universidad del Valle
  • References: <199811090215.VAA09297@smc.vnet.net.>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Naum,
try
pointlist=Table[{ArcSin[Random[Real,{-1,1}],
Random[Real,{-pi,pi}]},{density}]

Jurgen


Naum Phleger wrote:
> 
>     I want to distribute vectors for a given vector field evenly over
> the surface of a sphere.  The easiest way that I have come up with is
> to generate a random list of {theta,fi} pairs.  This makes the field
> too dense at the north and south poles.  I would like to use a cosine
> distribution to be used in my random number generator so that I get a
> more uniform distribution.  Here is my code now, and what I would like
> it to look more like.
> 
> density is the total number of vectors
> 
> NOW:
>     pointlist=Table[{Random[Real,{ -pi/2 , pi/2 }], Random[Real,{ -pi ,
> pi }]},{density,i}]
> 
> DESIRED
>     pointlist=Table[{Random[CosDistribution,{ -pi/2 , pi/2 }],
> Random[Real,{ -pi , pi }]},{density,i}]
> 
>               -NAUM



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