Doc/lib/libwhrandom.tex

   1 \section{Standard Module \module{whrandom}}
   2 \label{module-whrandom}
   3 \stmodindex{whrandom}
   4
   5 This module implements a Wichmann-Hill pseudo-random number generator
   6 class that is also named \code{whrandom}.  Instances of the
   7 \code{whrandom} class have the following methods:
   8
   9 \begin{funcdesc}{choice}{seq}
  10 Chooses a random element from the non-empty sequence \var{seq} and returns it.
  11 \end{funcdesc}
  12
  13 \begin{funcdesc}{randint}{a, b}
  14 Returns a random integer \var{N} such that \code{\var{a}<=\var{N}<=\var{b}}.
  15 \end{funcdesc}
  16
  17 \begin{funcdesc}{random}{}
  18 Returns the next random floating point number in the range [0.0 ... 1.0).
  19 \end{funcdesc}
  20
  21 \begin{funcdesc}{seed}{x, y, z}
  22 Initializes the random number generator from the integers
  23 \var{x},
  24 \var{y}
  25 and
  26 \var{z}.
  27 When the module is first imported, the random number is initialized
  28 using values derived from the current time.
  29 \end{funcdesc}
  30
  31 \begin{funcdesc}{uniform}{a, b}
  32 Returns a random real number \var{N} such that \code{\var{a}<=\var{N}<\var{b}}.
  33 \end{funcdesc}
  34
  35 When imported, the \code{whrandom} module also creates an instance of
  36 the \code{whrandom} class, and makes the methods of that instance
  37 available at the module level.  Therefore one can write either
  38 \code{N = whrandom.random()} or:
  39 \begin{verbatim}
  40 generator = whrandom.whrandom()
  41 N = generator.random()
  42 \end{verbatim}
  43 %
  44 \begin{seealso}
  45 \seemodule{random}{generators for various random distributions}
  46 \seetext{Wichmann, B. A. \& Hill, I. D., ``Algorithm AS 183:
  47 An efficient and portable pseudo-random number generator'',
  48 \emph{Applied Statistics} 31 (1982) 188-190}
  49 \end{seealso}