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.

**Follow-Ups**:**Variables in ProbabilityDistribution have strange "scoping" mechanism***From:*CHARLES GILLINGHAM <cgillingham1@me.com>

**Re: Bug with ProbabilityDistribution***From:*CHARLES GILLINGHAM <cgillingham1@me.com>