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c++c++11randommt19937
Humam Helfawi
Humam Helfawi

Reputation: 20274

Reproduce the same result of the C++ 11 random generator

Is it guaranteed by the standard that if std::mt19937 was seeded by the same number, it will produce the same sequence of numbers on all platforms?

In other words, is its implementation well-defined by the standard or it is like std::rand() which was considered as implementation details?

Upvotes: 0

Views: 407

Answers (1)

Hatted Rooster
Hatted Rooster

Reputation: 36483

In [rand.eng.mars] 1-5 the passage basically sums up the implementation details for the mersenne twister algorithm.

std::mt19937 is just a typedef for 

using mt19937 =
      mersenne_twister_engine<uint_fast32_t,
       32,624,397,31,0x9908b0df,11,0xffffffff,7,0x9d2c5680,15,0xefc60000,18,1812433253>;

And all the standard says about the expected results is that :

Required behavior: The 10000 th consecutive invocation of a default-constructed object of type mt19937 shall produce the value 4123659995.

No other guarantees are made.

However, because the std::mersenne_twister_engine is required to follow the mersenne twister PRNG implementation it's implementation is well defined.

Upvotes: 6

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