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Fix and optimize von_mises_distribution class.

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From-SVN: r196436
This commit is contained in:
Ulrich Drepper 2013-03-04 16:24:58 +00:00 committed by Ulrich Drepper
parent 91c4e42106
commit 0388c91350
2 changed files with 20 additions and 13 deletions
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7
libstdc++-v3/ChangeLog
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@ -1,3 +1,10 @@
2013-03-04 Ulrich Drepper <drepper@gmail.com>
* include/ext/random (__gnu_cxx::von_mises_distribution<>):
Optimize generation function by pulling computation of __r into the
constructor for param_type. Also compare _M_mu in operator==.
Fix comment.
2013-03-02 Ulrich Drepper <drepper@gmail.com>
Add triangular and von Mises distributions.

26
libstdc++-v3/include/ext/random
View File

@ -2621,6 +2621,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
const _RealType __pi = __gnu_cxx::__math_constants<_RealType>::__pi;
_GLIBCXX_DEBUG_ASSERT(_M_mu >= -__pi && _M_mu <= __pi);
_GLIBCXX_DEBUG_ASSERT(_M_kappa >= _RealType(0));
auto __tau = std::sqrt(_RealType(4) * _M_kappa * _M_kappa
+ _RealType(1)) + _RealType(1);
auto __rho = ((__tau - std::sqrt(_RealType(2) * __tau))
/ (_RealType(2) * _M_kappa));
_M_r = (_RealType(1) + __rho * __rho) / (_RealType(2) * __rho);
}
_RealType
@ -2633,16 +2639,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
friend bool
operator==(const param_type& __p1, const param_type& __p2)
{ return __p1._M_kappa == __p2._M_kappa; }
{ return (__p1._M_mu == __p2._M_mu
&& __p1._M_kappa == __p2._M_kappa); }
private:
_RealType _M_mu;
_RealType _M_kappa;
_RealType _M_r;
};
/**
* @brief Constructs a beta distribution with parameters
* @brief Constructs a von Mises distribution with parameters
* @f$\mu@f$ and @f$\kappa@f$.
*/
explicit
@ -2727,20 +2734,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
= __gnu_cxx::__math_constants<result_type>::__pi;
std::__detail::_Adaptor<_UniformRandomNumberGenerator, result_type>
__aurng(__urng);
result_type __tau = (std::sqrt(result_type(4) * this->kappa()
* this->kappa() + result_type(1))
+ result_type(1));
result_type __rho = ((__tau - std::sqrt(result_type(2) * __tau))
/ (result_type(2) * this->kappa()));
result_type __r = ((result_type(1) + __rho * __rho)
/ (result_type(2) * __rho));
result_type __f;
while (1)
{
result_type __rnd = std::cos(__pi * __aurng());
__f = (result_type(1) + __r * __rnd) / (__r + __rnd);
result_type __c = this->kappa() * (__r - __f);
__f = (result_type(1) + __p._M_r * __rnd) / (__p._M_r + __rnd);
result_type __c = __p._M_kappa * (__p._M_r - __f);
result_type __rnd2 = __aurng();
if (__c * (result_type(2) - __c) > __rnd2)
@ -2756,7 +2756,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (__aurng() < result_type(0.5))
__res = -__res;
#endif
__res += this->mu();
__res += __p._M_mu;
if (__res > __pi)
__res -= result_type(2) * __pi;
else if (__res < -__pi)