cpython/Doc/lib/libwhrandom.tex

\section{\module{whrandom} ---
         Floating point pseudo-random number generator.}
\declaremodule{standard}{whrandom}

\modulesynopsis{Floating point pseudo-random number generator.}


This module implements a Wichmann-Hill pseudo-random number generator
class that is also named \code{whrandom}.  Instances of the
\code{whrandom} class have the following methods:

\begin{funcdesc}{choice}{seq}
Chooses a random element from the non-empty sequence \var{seq} and returns it.
\end{funcdesc}

\begin{funcdesc}{randint}{a, b}
Returns a random integer \var{N} such that \code{\var{a}<=\var{N}<=\var{b}}.
\end{funcdesc}

\begin{funcdesc}{random}{}
Returns the next random floating point number in the range [0.0 ... 1.0).
\end{funcdesc}

\begin{funcdesc}{seed}{x, y, z}
Initializes the random number generator from the integers
\var{x},
\var{y}
and
\var{z}.
When the module is first imported, the random number is initialized
using values derived from the current time.
\end{funcdesc}

\begin{funcdesc}{uniform}{a, b}
Returns a random real number \var{N} such that \code{\var{a}<=\var{N}<\var{b}}.
\end{funcdesc}

When imported, the \code{whrandom} module also creates an instance of
the \code{whrandom} class, and makes the methods of that instance
available at the module level.  Therefore one can write either 
\code{N = whrandom.random()} or:
\begin{verbatim}
generator = whrandom.whrandom()
N = generator.random()
\end{verbatim}
%
\begin{seealso}
\seemodule{random}{generators for various random distributions}
\seetext{Wichmann, B. A. \& Hill, I. D., ``Algorithm AS 183: 
An efficient and portable pseudo-random number generator'', 
\emph{Applied Statistics} 31 (1982) 188-190}
\end{seealso}