[rand.dist.bern.bin]. The evaluation function for this binomial distribution is hopefully just a placeholder. It is using the simplest and slowest method for computing the distribution and needs to be upgraded.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@103524 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/random b/include/random
index 811bc26..0f2c6ea 100644
--- a/include/random
+++ b/include/random
@@ -608,7 +608,62 @@
};
template<class IntType = int>
- class binomial_distribution;
+class binomial_distribution
+{
+public:
+ // types
+ typedef IntType result_type;
+
+ class param_type
+ {
+ public:
+ typedef binomial_distribution distribution_type;
+
+ explicit param_type(IntType t = 1, double p = 0.5);
+
+ IntType t() const;
+ double p() const;
+
+ friend bool operator==(const param_type& x, const param_type& y);
+ friend bool operator!=(const param_type& x, const param_type& y);
+ };
+
+ // constructors and reset functions
+ explicit binomial_distribution(IntType t = 1, double p = 0.5);
+ explicit binomial_distribution(const param_type& parm);
+ void reset();
+
+ // generating functions
+ template<class URNG> result_type operator()(URNG& g);
+ template<class URNG> result_type operator()(URNG& g, const param_type& parm);
+
+ // property functions
+ IntType t() const;
+ double p() const;
+
+ param_type param() const;
+ void param(const param_type& parm);
+
+ result_type min() const;
+ result_type max() const;
+
+ friend bool operator==(const binomial_distribution& x,
+ const binomial_distribution& y);
+ friend bool operator!=(const binomial_distribution& x,
+ const binomial_distribution& y);
+
+ template <class charT, class traits>
+ friend
+ basic_ostream<charT, traits>&
+ operator<<(basic_ostream<charT, traits>& os,
+ const binomial_distribution& x);
+
+ template <class charT, class traits>
+ friend
+ basic_istream<charT, traits>&
+ operator>>(basic_istream<charT, traits>& is,
+ binomial_distribution& x);
+};
template<class IntType = int>
class geometric_distribution;
@@ -2797,11 +2852,7 @@
// generating functions
template<class _URNG> result_type operator()(_URNG& __g)
{return (*this)(__g, __p_);}
- template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p)
- {
- return _STD::generate_canonical<double, numeric_limits<double>::digits>(__g)
- < __p.p();
- }
+ template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
// property functions
double p() const {return __p_.p();}
@@ -2820,6 +2871,14 @@
{return !(__x == __y);}
};
+template<class _URNG>
+inline
+bernoulli_distribution::result_type
+bernoulli_distribution::operator()(_URNG& __g, const param_type& __p)
+{
+ return (__g() - __g.min()) < __p.p() * (__g.max() - __g.min() + 1.);
+}
+
template <class _CharT, class _Traits>
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const bernoulli_distribution& __x)
@@ -2846,6 +2905,108 @@
return __is;
}
+template<class _IntType = int>
+class binomial_distribution
+{
+public:
+ // types
+ typedef _IntType result_type;
+
+ class param_type
+ {
+ result_type __t_;
+ double __p_;
+ public:
+ typedef binomial_distribution distribution_type;
+
+ explicit param_type(result_type __t = 1, double __p = 0.5)
+ : __t_(__t), __p_(__p) {}
+
+ result_type t() const {return __t_;}
+ double p() const {return __p_;}
+
+ friend bool operator==(const param_type& __x, const param_type& __y)
+ {return __x.__t_ == __y.__t_ && __x.__p_ == __y.__p_;}
+ friend bool operator!=(const param_type& __x, const param_type& __y)
+ {return !(__x == __y);}
+ };
+
+private:
+ param_type __p_;
+
+public:
+ // constructors and reset functions
+ explicit binomial_distribution(result_type __t = 1, double __p = 0.5)
+ : __p_(param_type(__t, __p)) {}
+ explicit binomial_distribution(const param_type& __p) : __p_(__p) {}
+ void reset() {}
+
+ // generating functions
+ template<class _URNG> result_type operator()(_URNG& __g)
+ {return (*this)(__g, __p_);}
+ template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
+
+ // property functions
+ result_type t() const {return __p_.t();}
+ double p() const {return __p_.p();}
+
+ param_type param() const {return __p_;}
+ void param(const param_type& __p) {__p_ = __p;}
+
+ result_type min() const {return 0;}
+ result_type max() const {return t();}
+
+ friend bool operator==(const binomial_distribution& __x,
+ const binomial_distribution& __y)
+ {return __x.__p_ == __y.__p_;}
+ friend bool operator!=(const binomial_distribution& __x,
+ const binomial_distribution& __y)
+ {return !(__x == __y);}
+};
+
+template<class _IntType>
+template<class _URNG>
+_IntType
+binomial_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
+{
+ bernoulli_distribution __bd(__p.p());
+ _IntType __r = 0;
+ _IntType __t = __p.t();
+ for (_IntType __i = 0; __i < __t; ++__i)
+ __r += __bd(__g);
+ return __r;
+}
+
+template <class _CharT, class _Traits, class _IntType>
+basic_ostream<_CharT, _Traits>&
+operator<<(basic_ostream<_CharT, _Traits>& __os,
+ const binomial_distribution<_IntType>& __x)
+{
+ __save_flags<_CharT, _Traits> _(__os);
+ __os.flags(ios_base::dec | ios_base::left);
+ _CharT __sp = __os.widen(' ');
+ __os.fill(__sp);
+ return __os << __x.t() << __sp << __x.p();
+}
+
+template <class _CharT, class _Traits, class _IntType>
+basic_istream<_CharT, _Traits>&
+operator>>(basic_istream<_CharT, _Traits>& __is,
+ binomial_distribution<_IntType>& __x)
+{
+ typedef binomial_distribution<_IntType> _Eng;
+ typedef typename _Eng::result_type result_type;
+ typedef typename _Eng::param_type param_type;
+ __save_flags<_CharT, _Traits> _(__is);
+ __is.flags(ios_base::dec | ios_base::skipws);
+ result_type __t;
+ double __p;
+ __is >> __t >> __p;
+ if (!__is.fail())
+ __x.param(param_type(__t, __p));
+ return __is;
+}
+
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_RANDOM