The discard member function of the mersenne_twister_engine class is unnecessarily inefficient. It currently discard elements one-by-one. It is possible to discard with higher granularity by discarding the entire internal buffer. The attached patch implements this. To avoid duplication a new internal member function is introduced which generates a new set of bits for the internal buffer. The operator() is changed to use it.
2012-08-22 Ulrich Drepper <drep...@gmail.com>
* include/bits/random.h (mersenne_twister_engine): Don't inline
discard here. New member function _M_gen_rand.
* include/bits/random.tcc (mersenne_twister_engine<>::_M_gen_rand):
New function. Extracted from operator().
(mersenne_twister_engine<>::discard): New implementation which
skips in large steps.
(mersenne_twister_engine<>::operator()): Use _M_gen_rand.
d-mersenne-discard
Description: Binary data
