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boost::random::linear_congruential_engine
// In header: <boost/random/linear_congruential.hpp> template<typename IntType, a, c, m> class linear_congruential_engine { public: // types typedef ; // construct/copy/destruct (); (); template<typename SeedSeq> (); template<typename It> (, ); // public member functions (); (); template<typename SeedSeq> (); template<typename It> (, ); (); template<typename Iter> (, ); (); // public static functions (); (); // friend functions template<typename CharT, typename Traits> (, linear_congruential_engine &); template<typename CharT, typename Traits> (, linear_congruential_engine &); // public data members static has_fixed_range; static multiplier; static increment; static modulus; static default_seed; };
Instantiations of class template linear_congruential_engine model a pseudo-random number generator . Linear congruential pseudo-random number generators are described in:
"Mathematical methods in large-scale computing units", D. H. Lehmer, Proc. 2nd Symposium on Large-Scale Digital Calculating Machines, Harvard University Press, 1951, pp. 141-146
Let x(n) denote the sequence of numbers returned by some pseudo-random number generator. Then for the linear congruential generator, x(n+1) := (a * x(n) + c) mod m. Parameters for the generator are x(0), a, c, m. The template parameter IntType shall denote an integral type. It must be large enough to hold values a, c, and m. The template parameters a and c must be smaller than m.
Note: The quality of the generator crucially depends on the choice of the parameters. User code should use one of the sensibly parameterized generators such as minstd_rand instead.
linear_congruential_engine
public
construct/copy/destruct();
Constructs a
, using the default seed linear_congruential_engine
( x0);
Constructs a
, seeding it with linear_congruential_engine
x0
.
template<typename SeedSeq> ( seq);
Constructs a
, seeding it with values produced by a call to linear_congruential_engine
seq.generate()
.
template<typename It> ( first, last);
Constructs a
and seeds it with values taken from the itrator range [first, last) and adjusts first to point to the element after the last one used. If there are not enough elements, throws linear_congruential_engine
std::invalid_argument
.
first and last must be input iterators.
linear_congruential_engine
public member functions();
Calls seed(default_seed)
( x0_);
If c mod m is zero and x0 mod m is zero, changes the current value of the generator to 1. Otherwise, changes it to x0 mod m. If c is zero, distinct seeds in the range [1,m) will leave the generator in distinct states. If c is not zero, the range is [0,m).
template<typename SeedSeq> ( seq);
Seeds a
using values from a SeedSeq. linear_congruential_engine
template<typename It> ( first, last);
seeds a
with values taken from the itrator range [first, last) and adjusts linear_congruential_engine
first
to point to the element after the last one used. If there are not enough elements, throws std::invalid_argument
.
first
and last
must be input iterators.
();
Returns the next value of the
. linear_congruential_engine
template<typename Iter> ( first, last);
Fills a range with random values
( z);
Advances the state of the generator by z
.
linear_congruential_engine
public static functions();
Returns the smallest value that the
can produce. linear_congruential_engine
();
Returns the largest value that the
can produce. linear_congruential_engine
linear_congruential_engine
friend functionstemplate<typename CharT, typename Traits> ( os, linear_congruential_engine & lcg);
Writes a
to a linear_congruential_engine
std::ostream
.
template<typename CharT, typename Traits> ( is, linear_congruential_engine & lcg);
Reads a
from a linear_congruential_engine
std::istream
.