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Re: GammaDistribution versus PoissonDistribution

  • To: mathgroup at smc.vnet.net
  • Subject: [mg79077] Re: GammaDistribution versus PoissonDistribution
  • From: "Jean-Marc Gulliet" <jeanmarc.gulliet at gmail.com>
  • Date: Wed, 18 Jul 2007 02:52:11 -0400 (EDT)
  • References: <589001.91066.qm@web26012.mail.ukl.yahoo.com>

On 7/17/07, Peter van Summeren <peter_van_summeren at yahoo.co.uk> wrote:
[snip]
> But, on my version 6.0 I could not see the whole GammaDistribution.
> Maybe it interfered with the PoissonDistribution.
> That was the question.

Hi Peter,

I see what you mean. If the graph of the gamma distribution seems to
be cut at the top for some values of a and b it is because the values
of the function are well beyond the range you specified for the
y-axis. Try the following with small values for a and b (you can
easily reach 100 and over, that is well above your setting of 0.2).

Manipulate[
  Plot[PDF[GammaDistribution[a, b], x], {x, 0, 30},
  PlotRange -> All], {{a, 1, "a"}, 0, 30}, {{b, 1, "b"}, 0.1, 2}]

Regards,
Jean-Marc

> with friendly greetings,
> Peter van Summeren
>
>
> ----- Original Message ----
> From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
> To: P_ter <peter_van_summeren at yahoo.co.uk>; mathgroup at smc.vnet.net
> Sent: Tuesday, 17 July, 2007 12:14:33 PM
> Subject: Re: GammaDistribution versus PoissonDistribution
>
> P_ter wrote:
> > I did this and what I am interested in is, that not always the graphics is
> visible in my version 6.0:
> > Manipulate[ Show[{
> >
> ListPlot[Table[{i,PDF[PoissonDistribution[m],i]},{i,0,30}]],
> > Plot[PDF[GammaDistribution[a,b],x],{x,0,30}]
> >                  },
> > PlotRange->{-.1,0.2},
> ---------------------^
> A square bracket is missing.
>
> > {{m,1,"m"},1,20},{{a,1,"a"},0,30},{{b,1,"b"},0.1,2}]
> > I hope I typed it all correctly.
> > Any suggestions?
> > with friendly greetings,
> > P_ter
>
> Not sure what the problem is: the expression below produces some neat
> plot of the functions.
>
> Manipulate[Show[{ListPlot[Table[{i,
> PDF[PoissonDistribution[m], i]},
>             {i, 0, 30}]],
>     Plot[PDF[GammaDistribution[a, b], x], {x, 0, 30}]},
>       PlotRange -> {-0.1, 0.2}], {{m, 1, "m"}, 1, 20},
>     {{a, 1, "a"}, 0, 30}, {{b, 1, "b"}, 0.1, 2}]
>
> $Version
>
> 6.0 for Microsoft Windows (32-bit) (April 20, 2007)
>
> Regards,
> Jean-Marc
>
>
>  ________________________________
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