Re: random variables
- To: mathgroup at smc.vnet.net
- Subject: [mg120461] Re: random variables
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Sun, 24 Jul 2011 03:19:14 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201107232352.TAA08648@smc.vnet.net>
- Reply-to: drmajorbob at yahoo.com
U=ChiSquareDistribution[n-1];
twoU=TransformedDistribution[2*u,u\[Distributed]U];
Through[{Mean,Variance,PDF}@twoU]
{2 (-1+n),8 (-1+n),Function[\[FormalX],\[Piecewise] (2^(1-n)
\[FormalX]^(-1+1/2 (-1+n)) E^(-\[FormalX]/4))/Gamma[1/2
(-1+n)] \[FormalX]>0
0 True
,Listable]}
Bobby
On Sat, 23 Jul 2011 18:52:50 -0500, paulvonhippel at yahoo
<paulvonhippel at yahoo.com> wrote:
> I would like to define a symbol representing a random variable, and
> then use that symbol in other expressions. It's not clear to me how to
> do that. For example, when I type the following input --
>
> U = ChiSquareDistribution[n - 1]
> V = 2*U
> W = 3*U
> Mean[V]
> Mean[W]
>
> -- I do not get the mean of the random variables V and W. I know I can
> get the desired answer by typing:
>
> V = TransformedDistribution[2*U,
> U \[Distributed] ChiSquareDistribution[n - 1]]
> W = TransformedDistribution[3*U,
> U \[Distributed] ChiSquareDistribution[n - 1]]
> Mean[V]
> Mean[W]
>
> But that requires me to redefine the distribution of U every time I
> need it.
>
> Is there a way to define U just once?
>
--
DrMajorBob at yahoo.com
- References:
- random variables
- From: paulvonhippel at yahoo <paulvonhippel@yahoo.com>
- random variables