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Re: geometric random distributionsby Moron (Curate) 
on Jun 08, 2007 at 07:18 UTC ( #619971=note: print w/ replies, xml )  Need Help?? 
(update: the probability density function of a random number generator is the derivative of the generating function, so in this case a cosine density shape is therefore being produced.) A simple integration is also needed for the triangular distribution: Its probability density function has a smooth gradient so the generator satisfies the equation dy/dx = gradient. So integrating that straight line function, gives the generating function: 1  (rand() ** (1+gradient))) would give a random number with a triangular probability density function coming out.
The reason the normal distribution is an exception deserving a special method is that its cumulative distribution function
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