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