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std::mersen...ister_engine(3)  C++ Standard Libary std::mersen...ister_engine(3)

NAME
     std::mersenne_twister_engine::mersenne_twister_engine		       -
     std::mersenne_twister_engine::mersenne_twister_engine

Synopsis
	mersenne_twister_engine()  :				     (1)  (since
     C++11)
	mersenne_twister_engine(default_seed) {}
	explicit  mersenne_twister_engine(  result_type  value );     (2) (since
     C++11)
	template< class SeedSeq  >				     (3)  (since
     C++11)
	explicit mersenne_twister_engine( SeedSeq& seq );
	mersenne_twister_engine(  const  mersenne_twister_engine&     (4) (since
     C++11)
	other );							(implic-
     itly declared)

	Constructs the pseudo-random number engine.

	1) The default constructor.
	2) Constructs the engine with a seed value value. Given \(2^w\)2w
	as p, the engine's initial state is determined as follows:
	 1. Sets \(X_{-n}\)X
	    -n to value % p.
	 2. For each integer i in [i - n, -1], sets \(X_i\)X
	    i  to  \([f \cdot (X_{i-1}\ \mathsf{xor}\ (X_{i-1}\ \mathsf{rshift}\
     (w-2)))+i\mod
	    n]\mod p\)[fA.(X
	    i-1 xor (X
	    i-1 rshift (w-2)))+i mod n] mod p, where \(\mathsf{xor}\)xor and
	    \(\mathsf{rshift}\)rshift stand for built-in bitwise XOR and bitwise
     right-shift
	    respectively.
	3) Constructs the engine with a seed sequence seq. Given std::size_t(w /
     32) + 1 as
	k, the engine's initial state is determined as follows:
	 1. Creates an invented array object a of length n * k.
	 2. Calls seq.generate(a + 0, a + n * k).
	 3. For each integer i in [-n, -1], sets \(X_{i}\)X
	    i to \((\sum^{k-1}_{j=0} a_{k(i+n)+j} \cdot 2^{32j}) \mod 2^w\)(ak-1
	    j=0 a
	    k(i+n)+jA.232j
	    ) mod 2w
	    .
	 4. If the most significant w a r bits of \(X_{-n}\)X
	    -n are zero, and if each of the other resulting \(X_{i}\)X
	    i is 0, changes \(X_{-n}\)X
	    -n to \(2^{w-1}\)2w-1
	    .
	This overload participates in overload resolution only if SeedSeq  meets
     the
	requirements of SeedSequence.
	4) The copy constructor. Upon construction, *this == other is true.

Parameters
	value - seed value to use in the initialization of the internal state
	seq   - seed sequence to use in the initialization of the internal state

Complexity
	1,2) \(\small{O(n)}\)O(n).
	3) Same as the complexity of the seq.generate call.
	4) \(\small{O(n)}\)O(n).

	Defect reports

	The  following	behavior-changing  defect  reports were applied retroac-
     tively to
	previously published C++ standards.

	  DR	Applied to	  Behavior as published 	Correct behavior
	P0935R0 C++11	   the default constructor was explicit made implicit

See also
	seed	sets the current state of the engine
	(C++11) (public member function)

http://cppreference.com 	   2024.06.10	   std::mersen...ister_engine(3)
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