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std::mersen...ister_engine(3) C++ Standard Libarystd::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	);							  (im-
       plicitly	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	 \([f	 \cdot	 (X_{i-1}\   \mathsf{xor}\   (X_{i-1}\
       \mathsf{rshift}\	(w-2)))+i\mod
	      n]\mod p\)[f(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  \((\sum^{k-1}_{j=0}  a_{k(i+n)+j}	\cdot  2^{32j})	  \mod
       2^w\)(k-1
	      j=0 a
	      k(i+n)+j232j
	      )	mod 2w
	      .
	   4. If the most significant w	 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  be-
       havior
	  P0935R0  C++11       the  default  constructor was explicit made im-
       plicit

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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