2010.04.09 23:46, Steven Watanabe rašė:
AMDG
What exactly would this constructor do? It looks to me as though, if it jest set the initial state, then (for a one-dimensional generator) the effective result would be as though you xor'ed the initial state with the normal values of the generator.
This could used, for example, to initialize nextq to specific values that nextq would be unlikely to acquire otherwise. This scenario is admittedly a little bit contrived.
The following test case breaks because min and max are not defined correctly #include <boost/random/niederreiter_base2.hpp>
#define BOOST_TEST_MAIN #include <boost/test/unit_test.hpp>
BOOST_AUTO_TEST_CASE(test_niederreiter_base2_1d) { boost::niederreiter_base2_1d gen; for(int i = 0; i < 100; ++i) { int val = gen(); BOOST_CHECK_GE(val, (gen.min)()); BOOST_CHECK_LE(val, (gen.max)()); } }
Patched version in Vault. The fix was very trivial.
Finally, since the algorithm does a lot of bit-twiddling, would uint32_t be more appropriate than int?
You mean those typedefs of niederreiter_base2? Does not really matter. You could, for example instantiate template class niederreiter_base2 like this: niederreiter_base2<long, D, 1, (1 << 63)> gen; [1] Scaling down to the [0, 1]^D unit hypercube you would get more precision this way. (Of course, you could use uint32_t, too, and the typedef would look like this: niederreiter_base2<uint32_t, D, 1, (1U << 32) /*!*/> [2], but g++ complains about left shift count >= width of type, and spits out a warning in the instantiation site.) I think this option could be best left to users, who know what they want. Speaking of discard member function, I improved it in a way that makes more sense to me. According to the draft, discard(z) ought to behave as if z consecutive operator() invocations were executed. I refined this to be Dimension*z, so discard(z) now actually discards z consecutive s-dimensional vectors (s = Dimension). In 1-dimensional case the behaviour is the same as dictated by the standard. J. [1] On x86_64 platform long has 64 bits. [2] Tested with long and uint32_t, too, and aforementioned examples would produce the exact same sequence as int instantiation (scaled down to [0, 1]^D with uniform_real), the only difference being precision of division.