Doc/lib/libwhrandom.tex

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