# [pstricks] adding noise to a signal

jmpapy Jean-Michel.Papy at esat.kuleuven.ac.be
Thu Oct 7 15:17:17 CEST 2004

yes very good !!
I did not know the existence of a postscript pseudo-random generator.

However, this sequence seems to be drawn from a uniform distribution.
I'll try to transform it into a normal distribution, it should not be so
difficult ;-)

thanks again Herbert

JM

Quoting Herbert Voss <Herbert.Voss at alumni.TU-Berlin.DE>:

> jmpapy wrote:
>
> > does anybody knows how to generate a realization of a normally
> > distributed random variable b(n) and to add it to an existing
> > discrete-time signal s(n) drawn using pstricks ?
>
> something like this??
>
> Herbert
>
> \documentclass[a4paper,10pt]{article}
> \begin{document}
>
> \pstVerb{
>    rrand srand % initializes the random generator
> }
> \begin{pspicture}(-5,-0.2)(5,5)
> \psline{-}(-5,0)(5,0)
> \psplot[linecolor=red,plotpoints=50,showpoints=true,linestyle=none]
{-1}{3}{%
>    4.7 39.48 x 1 neg add 2 exp mul 1 2 exp add div
>    rand          % a random integer 0...2^31 - 1
>    2147483647    % 2^31 - 1
>    div add       % now rand is between 0...1
> }
> \end{pspicture}
>
> \vspace{1cm}
> \begin{pspicture}(-5,-0.2)(5,5)
> \psline{-}(-5,0)(5,0)
> \psplot[linecolor=red,plotpoints=50,showpoints=true,linestyle=none]
{-1}{3}{%
>    4.7 39.48 x 1 neg add 2 exp mul 1 2 exp add div
>    rand 2147483647 div add %
> }
> \end{pspicture}
>
> \end{document}
>
>
>
> --
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