##### cppreference.com

##### Search

Create account

##### Namespaces

- Page
- Discussion

##### Variants

##### Views

- View
- Edit
- History

##### Actions

# std::mersenne_twister_engine::mersenne_twister_engine

From cppreference.com
< cpp‎ | numeric‎ | random‎ | mersenne twister engine

[edit template]

explicit mersenne_twister_engine( result_type value = default_seed ); | (1) | (since C++11)
template< class Sseq > explicit mersenne_twister_engine( Sseq& s ); | (2) | (since C++11)
mersenne_twister_engine( const mersenne_twister_engine& ); | (3) | (since C++11) (implicitly declared)

Constructs the pseudo-random number engine.

1) Constructs the engine and initializes the state (`n` values X
i of type `result_type`) as follows: value mod 2w
is used to initialize X
0 and the rest are initialized iteratively, for i=1-n,...,-1, each X
i is initialized to [f·(X
i-1xor(X
i-1rshift(w-2)))+i mod n] mod 2w
2) Constructs the engine and initializes the state by calling s.generate(a, a+n*k) where a is an array of length n*k and k is ceil(w/32) and then, iteratively for i=-n,...,-1, setting each element of the engine state X
i to (Σk-1
j=0a
k(i+n)+j}·232j
) mod 2w
, and finally if the most significant w-r bits of X
0 are zero, and if all other X
i are zero, replacing X
0 with 2w-1
.

Note: initialization requirements are based on the 2002 version of Mersenne Twister, mt19937ar.c

The overload (2) only participates in overload resolution if `Sseq` qualifies as a `SeedSequence`. In particular, it is excluded from the set of candidate functions if `Sseq` is convertible to `result_type`.

### [edit] Parameters

value | - | seed value to use in the initialization of the internal state
s | - | seed sequence to use in the initialization of the internal state

### [edit] Complexity

linear in `n` (the state size)

### [edit] See also

seed | sets the current state of the engine (public member function) [edit]

Retrieved from "http://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random/mersenne_twister_engine/mersenne_twister_engine&oldid=50983"