mirror of https://github.com/CGAL/cgal
108 lines
4.0 KiB
TeX
108 lines
4.0 KiB
TeX
% =============================================================================
|
|
% The CGAL Reference Manual
|
|
% Section: Random Numbers Generator
|
|
% -----------------------------------------------------------------------------
|
|
% file : Kernel/spec/Random.tex
|
|
% author: Sven Schönherr (sven@inf.fu-berlin.de)
|
|
% -----------------------------------------------------------------------------
|
|
% $Revision$
|
|
% $Date$
|
|
% =============================================================================
|
|
|
|
\begin{ccClass}{CGAL_Random}
|
|
\ccSection{Random Numbers Generator}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccDefinition
|
|
|
|
An instance of type \ccClassName\ is a random numbers generator. It
|
|
allows to generate uniformly distributed random \ccc{bool}s,
|
|
\ccc{int}s and \ccc{double}s. It can be used as the random number
|
|
generating function object in the STL algorithm \ccc{random_shuffle}.
|
|
|
|
Instances of \ccClassName\ can be seen as input streams. Different
|
|
streams are \emph{independent} of each other, i.e.\ the sequence of
|
|
numbers from one stream does \emph{not} depend upon how many numbers
|
|
were extracted from the other streams.
|
|
|
|
It can be very useful, e.g.\ for debugging, to reproduce a sequence of
|
|
random numbers. This can be done by either initialising
|
|
deterministically or using the seed functions as described below.
|
|
|
|
\ccInclude{CGAL/Random.h}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccHeading{Global Variables}
|
|
|
|
\ccVariable{ CGAL_Random CGAL_random;}{
|
|
This global variable is used as the
|
|
default random numbers generator.}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccTypes
|
|
|
|
\ccUnchecked
|
|
\ccNestedType{Seed}{Seed type.}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccCreation
|
|
\ccCreationVariable{random}
|
|
|
|
\ccConstructor{ CGAL_Random( );}{
|
|
introduces a variable \ccVar\ of type \ccClassTemplateName.}
|
|
|
|
\ccConstructor{ CGAL_Random( Seed seed);}{
|
|
introduces a variable \ccVar\ of type \ccClassTemplateName\
|
|
and initializes it's internal seed with \ccc{seed}.}
|
|
|
|
\ccConstructor{ CGAL_Random( long init);}{
|
|
introduces a variable \ccVar\ of type \ccClassTemplateName\
|
|
and initializes it's internal seed using \ccc{init}. Equal
|
|
values for \ccc{init} result in equal sequences of random
|
|
numbers.}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccOperations
|
|
|
|
\ccMemberFunction{ bool get_bool( );}{
|
|
returns a random \ccc{bool}.}
|
|
|
|
\ccMemberFunction{ int get_int( int lower, int upper);}{
|
|
returns a random \ccc{int} from the interval
|
|
$[\mbox{\ccc{lower},\ccc{upper}})$.}
|
|
|
|
\ccMemberFunction{ double get_double( double lower = 0.0,
|
|
double upper = 1.0);}{
|
|
returns a random \ccc{double} from the interval
|
|
$[\mbox{\ccc{lower},\ccc{upper}})$.}
|
|
|
|
\ccMemberFunction{ int operator() ( int upper);}{
|
|
returns \ccVar\ccc{.get_int( 0, upper)}.}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccHeading{Seed Functions}
|
|
|
|
\ccMemberFunction{ void save_seed( Seed& seed) const;}{
|
|
saves the current internal seed in \ccc{seed}.}
|
|
|
|
\ccMemberFunction{ void restore_seed( Seed const& seed);}{
|
|
restores the internal seed from \ccc{seed}.}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccHeading{Equality Test}
|
|
|
|
\ccMemberFunction{ bool operator == ( CGAL_Random const& random2) const;}{
|
|
returns \ccc{true}, iff \ccVar\ and \ccc{random2} have equal
|
|
internal seeds.}
|
|
|
|
% -----------------------------------------------------------------------------
|
|
\ccImplementation
|
|
|
|
We use the C library function \ccc{erand48} to generate the random
|
|
numbers, i.e.\ the sequence of numbers depends on the implementation
|
|
of \ccc{erand48} on your specific platform.
|
|
|
|
\end{ccClass}
|
|
|
|
% ===== EOF ===================================================================
|