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%D \module
%D [ file=supp-ran,
%D version=1998.01.21,
%D title=\CONTEXT\ Support Macros,
%D subtitle=Random Number Generation,
%D author=Hans Hagen,
%D date=\currentdate,
%D copyright={PRAGMA / Hans Hagen \& Ton Otten}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.
\writestatus{loading}{Third Party Macros / Random Number Generation}
%D \macros
%D {getrandomcount, getrandomdimen,
%D getrandomfloat, getrandomnumber,
%D setrandomseed, getrandomseed}
%D
%D This module load Donald Arseneau's generic file
%D \type{random.tex}. A small shell is needed because we
%D redefine some \TEX\ primitives. We also use different names
%D for the two generators and add an extra one.
%D
%D \starttyping
%D \getrandomcount \countregister {minimum} {maximum}
%D \getrandomdimen \dimenregister {minimum} {maximum}
%D \getrandomnumber \macroname {minimum} {maximum}
%D \getrandomfloat \macroname {minimum} {maximum}
%D \stoptyping
%D
%D Of course the file \type{random.tex} needs to be present.
%D To prevent name clashes, the \CONTEXT\ distribution
%D contains a copy in \type {thrd-ran.tex}.
%D
%D The randomseed can be set by:
%D
%D \starttyping
%d \setrandomseed{number>0}
%D \stoptyping
%D
%D and get by:
%D
%D \starttyping
%D \getrandomseed\randomseed
%D \stoptyping
\ifx\nextrandom\undefined
\readfile{random.tex}
{\writestatus{loading}{Donald Arseneau's 'random.tex' (found)}}
{\writestatus{loading}{Donald Arseneau's 'random.tex' (not found)}}
\fi
\ifx\nextrandom\undefined
\writestatus{loading}{using fake randomizer}
\newcount\randomi
\def\setrandim#1#2#3{\scratchdimen #2\relax#1\scratchdimen }
\def\setrannum#1#2#3{\scratchcounter#2\relax#1\scratchcounter}
\let\nextrandom\relax
\fi
\ifx\nextrandom\undefined \endinput \fi
\ifx\normaluniformdeviate\undefined
\let\verynormalnextrandom\nextrandom
\def\normalnextrandom
{\bgroup
\let\time \normaltime
\let\day \normalday
\let\month\normalmonth
\let\year \normalyear
\verynormalnextrandom
\egroup}
\else
% Yet untested.
\writestatus{loading}{using tex's built in randomizer (overloading macro)}
% For the meaning of the magic number, see \type {thrd-ran.tex}.
% \def\normalnextrandom
% {\setrandomseed\randomi
% \global\randomi\normaluniformdeviate2147483647\relax}
% Taco suggested to use the following alternative because \type
% {\normaluniformdeviate} can return a zero (as expected) while
% Donalds's alternative has a minimum of~1.
\beginTEX
\def\nextrandom
{\normalsetrandomseed\randomi
\global\randomi\normaluniformdeviate2147483646%
\global\advance\randomi\plusone}
\endTEX
\beginETEX \numexpr
\def\nextrandom
{\normalsetrandomseed\randomi
\global\randomi\numexpr\normaluniformdeviate2147483646+1\relax}
\endETEX
\let\normalnextrandom\nextrandom
\fi
\def\nextrandom
{\bgroup
\normalnextrandom
\gdef\nextrandom{\ifcase\randomseedfrozen\normalnextrandom\fi}%
\egroup}
\chardef\randomseedfrozen\zerocount
\def\freezerandomseed
{\ifcase\randomseedfrozen
\nextrandom \global\chardef\randomseedfrozen\plusone
\fi}
\def\defrostrandomseed
{\ifcase\randomseedfrozen\else
\global\chardef\randomseedfrozen\zerocount \nextrandom
\fi}
\let\getrandomcount\setrannum
\let\getrandomdimen\setrandim
\def\getrandomnumber#1#2#3%
{\getrandomcount\scratchcounter{#2}{#3}%
\edef#1{\the\scratchcounter}}
\def\getrandomfloat#1#2#3%
{\getrandomdimen\scratchdimen{#2\points}{#3\points}%
\edef#1{\withoutpt\the\scratchdimen}}
\unexpanded \def\setrandomseed#1%
{\global\randomi#1\relax} % global added
\unexpanded \def\getrandomseed#1%
{\edef#1{\number\randomi}}
\def\getnewrandomseed#1%
{\setrandomseed\minusone % signals thrd-ran to auto reseed
\nextrandom % this signal is needed for the
#1\randomi} % pseudo randomizer (see: third-ran)
\endinput
|
