[pstricks] [Fwd: Re: binom_distribution]

Herbert Voss LaTeX at zedat.fu-berlin.de
Mon Apr 17 12:57:50 CEST 2006

Poul Riis wrote:
> To my knowledge a binomial distribution is defined for integral values
> only.

you mean integer values.
that's correct, but the lines are connected to show that
the binomial distribution goes into the normal one for n->\infty

> I don't fully understand why the following seems to work...
> - And furthermore, I don't understand why it doesn't work for all values
> of n and p!?

the starting value (k=0) is (1-p)^n, which is a problem for n>125,
e.g. 0.5^125\approx 2.35e-38, which is nearly the smallest value
PostScript can handle.

The latest pst-func.tex (from http://perce.de/LaTeX/pst-func/)
has two macros \psBinomial and \psBinomialN for the normalized
distribution. Attached an example image of this code:



\uput[-90](7,0){$k$} \uput[90](0,0.5){$P(X=k)$}

\uput[-90](4,0){$z$} \uput[90](0,0.5){$P(Z=z)$}


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