std::mersenne_twister_engine<UIntType,w,n,m,r,a,u,d,s,b,t,c,l,f>::mersenne_twister_engine
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(1) | (since C++11) |
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(2) | (since C++11) |
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(3) | (since C++11) |
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(4) | (since C++11) (implicitly declared) |
Constructs the pseudo-random number engine.
1) Default constructor. Seeds the engine with
default_seed.
2) Constructs the engine and initializes the state (
n values Xi of type result_type) as follows: value mod 2w is used to initialize X0 and the rest are initialized iteratively, for i=1-n,...,-1, each Xi is initialized to [f·(Xi-1xor(Xi-1rshift(w-2)))+i mod n] mod 2w
3) 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 Xi to (Σk-1j=0ak(i+n)+j}·232j) mod 2w, and finally if the most significant w-r bits of X0 are zero, and if all other Xi are zero, replacing X0 with 2w-1.
Note: initialization requirements are based on the 2002 version of Mersenne Twister, mt19937ar.c
The overload (3) 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.
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 |
Complexity
Linear in n (the state size).
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 | default constructor was explicit | made implicit |
See also
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(C++11)
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sets the current state of the engine (public member function) |
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