<font face="Arial, Helvetica, sans-serif">Dear Herbert<br>
<br>
May I submit a code modification to pst-func to bring \psPoisson in line with \psBinomial and allow a recursive<br>
implementation of the Poisson distribution. Here is the relevant code with the suggested changes:<br>
<br>
% pst-func.tex<br>
.<br>
.<br>
<br>
\def\fileversion{0.49}<br>
\def\filedate{2007/12/23}<br>
.<br>
.<br>
etc<br>
.<br>
\def\psPoisson@i#1#2{%<br>
\begin@SpecialObj%<br>
\addto@pscode{<br>
/scx { \pst@number\psxunit mul } def<br>
/scy { \pst@number\psyunit mul } def<br>
/N #1 def<br>
/lambda #2 def<br>
/elambda Euler #2 neg exp def % e^-lambda<br>
/dx \psFunc@barwidth 2 div def<br>
/kOld dx neg def<br>
kOld scx 0 moveto % starting point<br>
/Y elambda def % start value<br>
0 1 N { % N times<br>
/k exch def % save loop variable<br>
%%%%%%%% GC modified 2007-08-24<br>
% k 0 eq { /kFaculty 1 def }{ /kFaculty kFaculty k mul def } ifelse % <- - - original<br>
% /Y lambda k exp kFaculty div elambda mul def % <- - - lines<br>
k 0 eq { /Y elambda def }{ /Y Y lambda mul k div def } ifelse % <- - - new code here<br>
%%%%%%%% GC modified end<br>
kOld scx 0 L kOld scx Y scy L k dx add scx Y scy L<br>
\ifPst@markZeros k dx add scx 0 L \fi<br>
\ifPst@printValue<br>
gsave \psk@PSfont findfont \psk@fontscale scalefont setfont<br>
Y \psk@valuewidth string cvs<br>
k scx \psk@fontscale 2 div add<br>
Y scy \pst@number\pslabelsep add moveto<br>
90 rotate show grestore<br>
\fi<br>
/kOld kOld 1 add def<br>
} for<br>
\ifPst@markZeros\else k dx add scx 0 L \fi % last line down to x-axis<br>
}%<br>
\psk@fillstyle<br>
\pst@stroke<br>
\end@SpecialObj%<br>
}<br>
.<br>
.<br>
etc<br>
<br>
This now allows \psPoisson{N}{mu} to work with N>26.<br>
<br>
Another suggestion if I may. To avoid having to use psclip, how about an implementation of \psBinomial and \psPoisson which limits the output of rectangles on both sides, for example <br>
<br>
\psPoisson{M}{N}{mu} which plots for M <= x <= N rather than 0 to N <br>
<br>
I am thinking of making changes myself. Would you allow this as useful?<br>
<br>
Gerry Coombes<br>
<br>
<br>
<br>
<br>
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