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std::mersenne_twister_engine<UIntType,w,n,m,r,a,u,d,s,b,t,c,l,f>::mersenne_twister_engine

From cppreference.com
 
 
 
 
std::mersenne_twister_engine
Member functions
mersenne_twister_engine::mersenne_twister_engine
(C++11)
Generation
Characteristics
Non-member functions
(C++11)(C++11)(until C++20)
(C++11)(C++11)
 
mersenne_twister_engine() : mersenne_twister_engine(default_seed) {}
(1) (since C++11)
explicit mersenne_twister_engine( result_type value );
(2) (since C++11)
template< class SeedSeq >
explicit mersenne_twister_engine( SeedSeq& seq );
(3) (since C++11)
mersenne_twister_engine( const mersenne_twister_engine& other );
(4) (since C++11)
(implicitly declared)

Constructs the pseudo-random number engine.

1) The default constructor.
2) Constructs the engine with a seed value value. Given 2w
as p, the engine's initial state is determined as follows:
  1. Sets X
    -n
    to value % p.
  2. For each integer i in [i - n-1], sets X
    i
    to [f·(X
    i-1
    xor (X
    i-1
    rshift (w-2)))+i mod n] mod p
    , where xor and 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
    to (∑k-1
    j=0
    a
    k(i+n)+j
    ·232j
    ) mod 2w
    .
  4. If the most significant w − r bits of X
    -n
    are zero, and if each of the other resulting X
    i
    is 0, changes X
    -n
    to 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.

Contents

[edit] 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

[edit] Complexity

1,2) O(n).
3) Same as the complexity of the seq.generate call.
4) O(n).

[edit] Defect reports

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

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

[edit] See also

(C++11)
sets the current state of the engine
(public member function) [edit]