diff options
Diffstat (limited to 'boost/random/binomial_distribution.hpp')
| -rw-r--r-- | boost/random/binomial_distribution.hpp | 54 |
1 files changed, 27 insertions, 27 deletions
diff --git a/boost/random/binomial_distribution.hpp b/boost/random/binomial_distribution.hpp index 3efc905746..78d1a123a4 100644 --- a/boost/random/binomial_distribution.hpp +++ b/boost/random/binomial_distribution.hpp @@ -278,18 +278,18 @@ private: m = static_cast<IntType>((t+1)*p); if(use_inversion()) { - q_n = pow((1 - p), static_cast<RealType>(t)); + _u.q_n = pow((1 - p), static_cast<RealType>(t)); } else { - btrd.r = p/(1-p); - btrd.nr = (t+1)*btrd.r; - btrd.npq = t*p*(1-p); - RealType sqrt_npq = sqrt(btrd.npq); - btrd.b = 1.15 + 2.53 * sqrt_npq; - btrd.a = -0.0873 + 0.0248*btrd.b + 0.01*p; - btrd.c = t*p + 0.5; - btrd.alpha = (2.83 + 5.1/btrd.b) * sqrt_npq; - btrd.v_r = 0.92 - 4.2/btrd.b; - btrd.u_rv_r = 0.86*btrd.v_r; + _u.btrd.r = p/(1-p); + _u.btrd.nr = (t+1)*_u.btrd.r; + _u.btrd.npq = t*p*(1-p); + RealType sqrt_npq = sqrt(_u.btrd.npq); + _u.btrd.b = 1.15 + 2.53 * sqrt_npq; + _u.btrd.a = -0.0873 + 0.0248*_u.btrd.b + 0.01*p; + _u.btrd.c = t*p + 0.5; + _u.btrd.alpha = (2.83 + 5.1/_u.btrd.b) * sqrt_npq; + _u.btrd.v_r = 0.92 - 4.2/_u.btrd.b; + _u.btrd.u_rv_r = 0.86*_u.btrd.v_r; } } @@ -303,24 +303,24 @@ private: while(true) { RealType u; RealType v = uniform_01<RealType>()(urng); - if(v <= btrd.u_rv_r) { - u = v/btrd.v_r - 0.43; + if(v <= _u.btrd.u_rv_r) { + u = v/_u.btrd.v_r - 0.43; return static_cast<IntType>(floor( - (2*btrd.a/(0.5 - abs(u)) + btrd.b)*u + btrd.c)); + (2*_u.btrd.a/(0.5 - abs(u)) + _u.btrd.b)*u + _u.btrd.c)); } - if(v >= btrd.v_r) { + if(v >= _u.btrd.v_r) { u = uniform_01<RealType>()(urng) - 0.5; } else { - u = v/btrd.v_r - 0.93; + u = v/_u.btrd.v_r - 0.93; u = ((u < 0)? -0.5 : 0.5) - u; - v = uniform_01<RealType>()(urng) * btrd.v_r; + v = uniform_01<RealType>()(urng) * _u.btrd.v_r; } RealType us = 0.5 - abs(u); - IntType k = static_cast<IntType>(floor((2*btrd.a/us + btrd.b)*u + btrd.c)); + IntType k = static_cast<IntType>(floor((2*_u.btrd.a/us + _u.btrd.b)*u + _u.btrd.c)); if(k < 0 || k > _t) continue; - v = v*btrd.alpha/(btrd.a/(us*us) + btrd.b); + v = v*_u.btrd.alpha/(_u.btrd.a/(us*us) + _u.btrd.b); RealType km = abs(k - m); if(km <= 15) { RealType f = 1; @@ -328,13 +328,13 @@ private: IntType i = m; do { ++i; - f = f*(btrd.nr/i - btrd.r); + f = f*(_u.btrd.nr/i - _u.btrd.r); } while(i != k); } else if(m > k) { IntType i = k; do { ++i; - v = v*(btrd.nr/i - btrd.r); + v = v*(_u.btrd.nr/i - _u.btrd.r); } while(i != m); } if(v <= f) return k; @@ -343,18 +343,18 @@ private: // final acceptance/rejection v = log(v); RealType rho = - (km/btrd.npq)*(((km/3. + 0.625)*km + 1./6)/btrd.npq + 0.5); - RealType t = -km*km/(2*btrd.npq); + (km/_u.btrd.npq)*(((km/3. + 0.625)*km + 1./6)/_u.btrd.npq + 0.5); + RealType t = -km*km/(2*_u.btrd.npq); if(v < t - rho) return k; if(v > t + rho) continue; IntType nm = _t - m + 1; - RealType h = (m + 0.5)*log((m + 1)/(btrd.r*nm)) + RealType h = (m + 0.5)*log((m + 1)/(_u.btrd.r*nm)) + fc(m) + fc(_t - m); IntType nk = _t - k + 1; if(v <= h + (_t+1)*log(static_cast<RealType>(nm)/nk) - + (k + 0.5)*log(nk*btrd.r/(k+1)) + + (k + 0.5)*log(nk*_u.btrd.r/(k+1)) - fc(k) - fc(_t - k)) { @@ -372,7 +372,7 @@ private: RealType q = 1 - p; RealType s = p / q; RealType a = (t + 1) * s; - RealType r = q_n; + RealType r = _u.q_n; RealType u = uniform_01<RealType>()(urng); IntType x = 0; while(u > r) { @@ -417,7 +417,7 @@ private: } btrd; // for inversion RealType q_n; - }; + } _u; /// @endcond }; |