[pstricks] plotting a piecewise constant function (step function)

Herbert Voss Herbert.Voss at FU-Berlin.DE
Thu Oct 21 11:52:01 CEST 2010

Am 21.10.2010 09:52, schrieb Leon Free:

> I want to plot the binomial (n,p) cumulative distribution function (cdf)
> which is a right continuous function with jumps at each integer between
> 0 and n (or I want to plot any such function). I call this function
> cdf(x) with x begin any real number.
> I managed to get the graph I want for this function relying heavily on
> FP commands provided by the fp.sty package. Here is my code :

everything kann be done more easily on PostScript side. However,
with the pst-func.tex from http://texnik.dante.de/tex/generic/ you can also
use the \psGaussI (see attched figure, created with the commented
two lines in the example)


\@namedef{psds at dotline}{\pst at gdot{ 0 0 DS \tx at SD 0 0 moveto 12 0 lineto


%  \rput[lb](2,0){\psGaussI[xunit=2.72,plotpoints=11,
%     plotstyle=dots,dotstyle=dotline,linecolor=red]{-1}{3}}%
  \psline[linecolor=red](-1,0)(0,0)    % draw 1rst step of CDF
    [/N 10 def    % predefined values
     /p 0.3 def
     /q 1 p sub def
     /bc 1 def
     /cdf q N exp def
    ]{% x value is on stack
      /x1 x 1 add def
      /M N x1 sub def
      /BC bc N x sub mul x 1 add div def
      /ps BC Euler x1 p ln mul exp mul Euler M q ln mul exp mul def
      /CDF ps cdf add def
      /bc BC def
      /cdf CDF def



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