Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2014

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Bug with ProbabilityDistribution

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132540] Re: Bug with ProbabilityDistribution
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Thu, 10 Apr 2014 03:06:57 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Delivered-to: l-mathgroup@wolfram.com
  • Delivered-to: mathgroup-outx@smc.vnet.net
  • Delivered-to: mathgroup-newsendx@smc.vnet.net

On 4/9/14 at 4:14 AM, cgillingham1 at me.com (CHARLES GILLINGHAM) wrote:

>Evaluate this:

>ProbabilityDistribution[
>Piecewise[{{0, x1 == 1 && x2 == 1}, {1/2, x1 == 1 && x2 == 0}, {0,
>x1 == 0 && x2 == 1}, {1/2, x1 == 0 && x2 == 0}}], {x1, 0, 1,
>1}, {x2, 0, 1, 1}
>]
>PDF[%][{1, 1}]

>And you get:

>Undefined

>But the probability is obviously 0

>Is there something I am misunderstanding about how simple Boolean
>probability distributions should be set up?

Start with a fresh session and pay attention to the syntax
coloring. Note that x1 and x2 are undefined and your syntax does
not make these local variables. That is entering

f[x_]:=2 x

will cause x to be colored differently than your x1, x2 above.

You get undefined as a result since x1 and x2 are never defined.




  • Prev by Date: Re: Very simple question
  • Next by Date: Re: Very simple question
  • Previous by thread: Re: Bug with ProbabilityDistribution
  • Next by thread: Re: Bug with ProbabilityDistribution