...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::random::mersenne_twister
// In header: <boost/random/mersenne_twister.hpp> template<typename UIntType, int w, int n, int m, int r, UIntType a, int u, int s, UIntType b, int t, UIntType c, int l, UIntType val> class mersenne_twister { public: // types typedef UIntType result_type; // construct/copy/destruct mersenne_twister(); mersenne_twister(UIntType); template<typename It> mersenne_twister(It &, It); template<typename Generator> mersenne_twister(Generator &); // public member functions void seed(); void seed(UIntType); template<typename Generator> void seed(Generator &); template<typename It> void seed(It &, It); result_type min() const; result_type max() const; result_type operator()(); // public static functions static bool validation(result_type); static const int word_size; static const int state_size; static const int shift_size; static const int mask_bits; static const UIntType parameter_a; static const int output_u; static const int output_s; static const UIntType output_b; static const int output_t; static const UIntType output_c; static const int output_l; static const bool has_fixed_range; };
Instantiations of class template mersenne_twister model a pseudo-random number generator . It uses the algorithm described in
"Mersenne Twister: A 623-dimensionally equidistributed uniform pseudo-random number generator", Makoto Matsumoto and Takuji Nishimura, ACM Transactions on Modeling and Computer Simulation: Special Issue on Uniform Random Number Generation, Vol. 8, No. 1, January 1998, pp. 3-30.
Note | |
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The boost variant has been implemented from scratch and does not derive from or use mt19937.c provided on the above WWW site. However, it was verified that both produce identical output. |
The seeding from an integer was changed in April 2005 to address a weakness.
The quality of the generator crucially depends on the choice of the parameters. User code should employ one of the sensibly parameterized generators such as mt19937 instead.
The generator requires considerable amounts of memory for the storage of its state array. For example, mt11213b requires about 1408 bytes and mt19937 requires about 2496 bytes.
mersenne_twister
public
construct/copy/destructmersenne_twister();
Constructs a mersenne_twister
and calls seed()
.
mersenne_twister(UIntType value);
Constructs a mersenne_twister
and calls seed(value)
.
template<typename It> mersenne_twister(It & first, It last);
template<typename Generator> mersenne_twister(Generator & gen);
Constructs a mersenne_twister and calls seed(gen)
.
Note | |
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The copy constructor will always be preferred over the templated constructor. |
mersenne_twister
public member functionsvoid seed();
Calls seed
(result_type(5489)).
void seed(UIntType value);
Sets the state x(0) to v mod 2w. Then, iteratively, sets x(i) to (i + 1812433253 * (x(i-1) xor (x(i-1) rshift w-2))) mod 2w for i = 1 .. n-1. x(n) is the first value to be returned by operator().
template<typename Generator> void seed(Generator & gen);
Sets the state of this mersenne_twister to the values returned by n invocations of gen.
Complexity: Exactly n invocations of gen.
template<typename It> void seed(It & first, It last);
result_type min() const;
result_type max() const;
result_type operator()();