Swiftdiff options
Diffstat (limited to '3rdParty/Boost/src/boost/random/mersenne_twister.hpp')
| -rw-r--r-- | 3rdParty/Boost/src/boost/random/mersenne_twister.hpp | 90 |
1 files changed, 55 insertions, 35 deletions
diff --git a/3rdParty/Boost/src/boost/random/mersenne_twister.hpp b/3rdParty/Boost/src/boost/random/mersenne_twister.hpp index be60389..3878fee 100644 --- a/3rdParty/Boost/src/boost/random/mersenne_twister.hpp +++ b/3rdParty/Boost/src/boost/random/mersenne_twister.hpp @@ -9,7 +9,8 @@ * See http://www.boost.org for most recent version including documentation. * - * $Id: mersenne_twister.hpp 74867 2011-10-09 23:13:31Z steven_watanabe $ + * $Id$ * * Revision history + * 2013-10-14 fixed some warnings with Wshadow (mgaunard) * 2001-02-18 moved to individual header files */ @@ -41,5 +42,5 @@ namespace random { * pseudo-random number generator", Makoto Matsumoto and Takuji Nishimura, * ACM Transactions on Modeling and Computer Simulation: Special Issue on - * Uniform Random Number Generation, Vol. 8, No. 1, January 1998, pp. 3-30. + * Uniform Random Number Generation, Vol. 8, No. 1, January 1998, pp. 3-30. * @endblockquote * @@ -52,5 +53,5 @@ namespace random { * The seeding from an integer was changed in April 2005 to address a * <a href="http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/emt19937ar.html">weakness</a>. - * + * * The quality of the generator crucially depends on the choice of the * parameters. User code should employ one of the sensibly parameterized @@ -84,5 +85,5 @@ public: BOOST_STATIC_CONSTANT(UIntType, initialization_multiplier = f); BOOST_STATIC_CONSTANT(UIntType, default_seed = 5489u); - + // backwards compatibility BOOST_STATIC_CONSTANT(UIntType, parameter_a = a); @@ -93,5 +94,5 @@ public: BOOST_STATIC_CONSTANT(UIntType, output_c = c); BOOST_STATIC_CONSTANT(std::size_t, output_l = l); - + // old Boost.Random concept requirements BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); @@ -137,5 +138,5 @@ public: BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(mersenne_twister_engine, UIntType, value) { - // New seeding algorithm from + // New seeding algorithm from // http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/emt19937ar.html // In the previous versions, MSBs of the seed affected only MSBs of the @@ -148,6 +149,8 @@ public: x[i] = (f * (x[i-1] ^ (x[i-1] >> (w-2))) + i) & mask; } + + normalize_state(); } - + /** * Seeds a mersenne_twister_engine using values produced by seq.generate(). @@ -158,11 +161,5 @@ public: i = n; - // fix up the state if it's all zeroes. - if((x[0] & (~static_cast<UIntType>(0) << r)) == 0) { - for(std::size_t j = 1; j < n; ++j) { - if(x[j] != 0) return; - } - x[0] = static_cast<UIntType>(1) << (w-1); - } + normalize_state(); } @@ -174,13 +171,7 @@ public: i = n; - // fix up the state if it's all zeroes. - if((x[0] & (~static_cast<UIntType>(0) << r)) == 0) { - for(std::size_t j = 1; j < n; ++j) { - if(x[j] != 0) return; - } - x[0] = static_cast<UIntType>(1) << (w-1); - } + normalize_state(); } - + /** Returns the smallest value that the generator can produce. */ static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () @@ -189,5 +180,5 @@ public: static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () { return boost::low_bits_mask_t<w>::sig_bits; } - + /** Produces the next value of the generator. */ result_type operator()(); @@ -224,5 +215,5 @@ public: return os; } - + /** Reads a mersenne_twister_engine from a @c std::istream */ template<class CharT, class Traits> @@ -245,17 +236,17 @@ public: * and will thus produce identical sequences. */ - friend bool operator==(const mersenne_twister_engine& x, - const mersenne_twister_engine& y) + friend bool operator==(const mersenne_twister_engine& x_, + const mersenne_twister_engine& y_) { - if(x.i < y.i) return x.equal_imp(y); - else return y.equal_imp(x); + if(x_.i < y_.i) return x_.equal_imp(y_); + else return y_.equal_imp(x_); } - + /** * Returns true if the two generators are in different states. */ - friend bool operator!=(const mersenne_twister_engine& x, - const mersenne_twister_engine& y) - { return !(x == y); } + friend bool operator!=(const mersenne_twister_engine& x_, + const mersenne_twister_engine& y_) + { return !(x_ == y_); } private: @@ -334,4 +325,33 @@ private: /** + * Converts an arbitrary array into a valid generator state. + * First we normalize x[0], so that it contains the same + * value we would get by running the generator forwards + * and then in reverse. (The low order r bits are redundant). + * Then, if the state consists of all zeros, we set the + * high order bit of x[0] to 1. This function only needs to + * be called by seed, since the state transform preserves + * this relationship. + */ + void normalize_state() + { + const UIntType upper_mask = (~static_cast<UIntType>(0)) << r; + const UIntType lower_mask = ~upper_mask; + UIntType y0 = x[m-1] ^ x[n-1]; + if(y0 & (static_cast<UIntType>(1) << (w-1))) { + y0 = ((y0 ^ a) << 1) | 1; + } else { + y0 = y0 << 1; + } + x[0] = (x[0] & upper_mask) | (y0 & lower_mask); + + // fix up the state if it's all zeroes. + for(std::size_t j = 0; j < n; ++j) { + if(x[j] != 0) return; + } + x[0] = static_cast<UIntType>(1) << (w-1); + } + + /** * Given a pointer to the last element of the rewind array, * and the current size of the rewind array, finds an element @@ -355,5 +375,5 @@ private: // x(i-k) ... x(i) x(i+1) ... x(i-k+n-1) - UIntType x[n]; + UIntType x[n]; std::size_t i; }; @@ -469,5 +489,5 @@ mersenne_twister_engine<UIntType,w,n,m,r,a,u,d,s,b,t,c,l,f>::operator()() * and Takuji Nishimura, ACM Transactions on Modeling and * Computer Simulation: Special Issue on Uniform Random Number - * Generation, Vol. 8, No. 1, January 1998, pp. 3-30. + * Generation, Vol. 8, No. 1, January 1998, pp. 3-30. * @endblockquote */ @@ -483,5 +503,5 @@ typedef mersenne_twister_engine<uint32_t,32,351,175,19,0xccab8ee7, * and Takuji Nishimura, ACM Transactions on Modeling and * Computer Simulation: Special Issue on Uniform Random Number - * Generation, Vol. 8, No. 1, January 1998, pp. 3-30. + * Generation, Vol. 8, No. 1, January 1998, pp. 3-30. * @endblockquote */ |