random.tcc (negative_binomial_distribution<>::operator() (_UniformRandomNumberGenerator&, const param_type&): Tweak to use a class member gamma_distribution.

2009-06-11  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/bits/random.tcc
	(negative_binomial_distribution<>::operator()
	(_UniformRandomNumberGenerator&, const param_type&): Tweak to use a
	class member gamma_distribution.
	(negative_binomial_distribution<>::operator()
	(_UniformRandomNumberGenerator&)): Implement out of line here.
	(operator<<(basic_ostream<>&, negative_binomial_distribution<>),
	operator>>(basic_ostream<>&, negative_binomial_distribution<>): Adjust.
	(student_t_distribution<>::operator()
	(_UniformRandomNumberGenerator&, const param_type&): Move inline,
	simplify.
	(operator<<(basic_ostream<>&, student_t_distribution<>),
	operator>>(basic_ostream<>&, student_t_distribution<>): Adjust.
	(chi_squared_distribution<>::operator()
	(_UniformRandomNumberGenerator&, const param_type&): Move inline,
	tweak to use a class member gamma_distribution.
	(operator<<(basic_ostream<>&, chi_squared_distribution<>),
	operator>>(basic_ostream<>&, chi_squared_distribution<>): Adjust.
	(fisher_f_distribution<>::operator() (_UniformRandomNumberGenerator&,
	const param_type&): Move inline, tweak to use class member
	gamma_distributions.
	(operator<<(basic_ostream<>&, fisher_f_distribution<>),
	operator>>(basic_ostream<>&, fisher_f_distribution<>): Adjust.
	* include/bits/random.h: Adjust, minor tweaks.

From-SVN: r148393

3 files changed, 271 insertions, 262 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index b07378d..4173c75 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,7 +1,33 @@
+2009-06-11  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* include/bits/random.tcc
+	(negative_binomial_distribution<>::operator()
+	(_UniformRandomNumberGenerator&, const param_type&): Tweak to use a
+	class member gamma_distribution.
+	(negative_binomial_distribution<>::operator()
+	(_UniformRandomNumberGenerator&)): Implement out of line here.
+	(operator<<(basic_ostream<>&, negative_binomial_distribution<>),
+	operator>>(basic_ostream<>&, negative_binomial_distribution<>): Adjust.
+	(student_t_distribution<>::operator()
+	(_UniformRandomNumberGenerator&, const param_type&): Move inline,
+	simplify.
+	(operator<<(basic_ostream<>&, student_t_distribution<>),
+	operator>>(basic_ostream<>&, student_t_distribution<>): Adjust.
+	(chi_squared_distribution<>::operator()
+	(_UniformRandomNumberGenerator&, const param_type&): Move inline,
+	tweak to use a class member gamma_distribution.
+	(operator<<(basic_ostream<>&, chi_squared_distribution<>),
+	operator>>(basic_ostream<>&, chi_squared_distribution<>): Adjust.
+	(fisher_f_distribution<>::operator() (_UniformRandomNumberGenerator&,
+	const param_type&): Move inline, tweak to use class member
+	gamma_distributions.
+	(operator<<(basic_ostream<>&, fisher_f_distribution<>),
+	operator>>(basic_ostream<>&, fisher_f_distribution<>): Adjust.
+	* include/bits/random.h: Adjust, minor tweaks.
+
 2009-06-10  Tom Tromey  <tromey@redhat.com>
 
-	* python/libstdcxx/v6/printers.py (lookup_function): Remove extra
-	';'.
+	* python/libstdcxx/v6/printers.py (lookup_function): Remove extra ';'.
 	(build_libstdcxx_dictionary): Accept shortened form of
 	basic_string names.
 	(StdStringPrinter.to_string): Remove reference to WideEncoding.
diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h
index 8a21ae5..e8edbf0 100644
--- a/libstdc++-v3/include/bits/random.h
+++ b/libstdc++-v3/include/bits/random.h
@@ -2078,7 +2078,7 @@ namespace std
     private:
       param_type _M_param;
 
-      normal_distribution<result_type> _M_nd;
+      std::normal_distribution<result_type> _M_nd;
     };
 
   /**
@@ -2111,6 +2111,164 @@ namespace std
     operator>>(std::basic_istream<_CharT, _Traits>&,
 	       std::lognormal_distribution<_RealType>&);
 
+  
+  /**
+   * @brief A gamma continuous distribution for random numbers.
+   *
+   * The formula for the gamma probability density function is
+   * @f$ p(x|\alpha,\beta) = \frac{1}{\beta\Gamma(\alpha)}
+   *                         (x/\beta)^{\alpha - 1} e^{-x/\beta} @f$.
+   */
+  template<typename _RealType = double>
+    class gamma_distribution
+    {
+    public:
+      /** The type of the range of the distribution. */
+      typedef _RealType result_type;
+      /** Parameter type. */
+      struct param_type
+      {
+	typedef gamma_distribution<_RealType> distribution_type;
+	friend class gamma_distribution<_RealType>;
+
+	explicit
+	param_type(_RealType __alpha_val = _RealType(1),
+		   _RealType __beta_val = _RealType(1))
+	: _M_alpha(__alpha_val), _M_beta(__beta_val)
+	{
+	  _GLIBCXX_DEBUG_ASSERT(_M_alpha > _RealType(0));
+	  _M_initialize();
+	}
+
+	_RealType
+	alpha() const
+	{ return _M_alpha; }
+
+	_RealType
+	beta() const
+	{ return _M_beta; }
+
+      private:
+	void
+	_M_initialize();
+
+	_RealType _M_alpha;
+	_RealType _M_beta;
+
+	_RealType _M_malpha, _M_a2;
+      };
+
+    public:
+      /**
+       * @brief Constructs a gamma distribution with parameters
+       * @f$ \alpha @f$ and @f$ \beta @f$.
+       */
+      explicit
+      gamma_distribution(_RealType __alpha_val = _RealType(1),
+			 _RealType __beta_val = _RealType(1))
+      : _M_param(__alpha_val, __beta_val), _M_nd()
+      { }
+
+      explicit
+      gamma_distribution(const param_type& __p)
+      : _M_param(__p), _M_nd()
+      { }
+
+      /**
+       * @brief Resets the distribution state.
+       */
+      void
+      reset()
+      { _M_nd.reset(); }
+
+      /**
+       * @brief Returns the @f$ \alpha @f$ of the distribution.
+       */
+      _RealType
+      alpha() const
+      { return _M_param.alpha(); }
+
+      /**
+       * @brief Returns the @f$ \beta @f$ of the distribution.
+       */
+      _RealType
+      beta() const
+      { return _M_param.beta(); }
+
+      /**
+       * @brief Returns the parameter set of the distribution.
+       */
+      param_type
+      param() const
+      { return _M_param; }
+
+      /**
+       * @brief Sets the parameter set of the distribution.
+       * @param __param The new parameter set of the distribution.
+       */
+      void
+      param(const param_type& __param)
+      { _M_param = __param; }
+
+      /**
+       * @brief Returns the greatest lower bound value of the distribution.
+       */
+      result_type
+      min() const
+      { return result_type(0); }
+
+      /**
+       * @brief Returns the least upper bound value of the distribution.
+       */
+      result_type
+      max() const
+      { return std::numeric_limits<result_type>::max(); }
+
+      template<typename _UniformRandomNumberGenerator>
+	result_type
+	operator()(_UniformRandomNumberGenerator& __urng)
+	{ return this->operator()(__urng, this->param()); }
+
+      template<typename _UniformRandomNumberGenerator>
+	result_type
+	operator()(_UniformRandomNumberGenerator& __urng,
+		   const param_type& __p);
+
+    private:
+      param_type _M_param;
+
+      std::normal_distribution<result_type> _M_nd;
+    };
+
+  /**
+   * @brief Inserts a %gamma_distribution random number distribution
+   * @p __x into the output stream @p __os.
+   *
+   * @param __os An output stream.
+   * @param __x  A %gamma_distribution random number distribution.
+   *
+   * @returns The output stream with the state of @p __x inserted or in
+   * an error state.
+   */
+  template<typename _RealType, typename _CharT, typename _Traits>
+    std::basic_ostream<_CharT, _Traits>&
+    operator<<(std::basic_ostream<_CharT, _Traits>&,
+	       const std::gamma_distribution<_RealType>&);
+
+  /**
+   * @brief Extracts a %gamma_distribution random number distribution
+   * @p __x from the input stream @p __is.
+   *
+   * @param __is An input stream.
+   * @param __x  A %gamma_distribution random number generator engine.
+   *
+   * @returns The input stream with @p __x extracted or in an error state.
+   */
+  template<typename _RealType, typename _CharT, typename _Traits>
+    std::basic_istream<_CharT, _Traits>&
+    operator>>(std::basic_istream<_CharT, _Traits>&,
+	       std::gamma_distribution<_RealType>&);
+
 
   /**
    * @brief A chi_squared_distribution random number distribution.
@@ -2144,12 +2302,12 @@ namespace std
 
       explicit
       chi_squared_distribution(_RealType __n = _RealType(1))
-      : _M_param(__n)
+      : _M_param(__n), _M_gd(__n / 2)
       { }
 
       explicit
       chi_squared_distribution(const param_type& __p)
-      : _M_param(__p)
+      : _M_param(__p), _M_gd(__p.n() / 2)
       { }
 
       /**
@@ -2157,7 +2315,7 @@ namespace std
        */
       void
       reset()
-      { }
+      { _M_gd.reset(); }
 
       /**
        *
@@ -2198,15 +2356,22 @@ namespace std
       template<typename _UniformRandomNumberGenerator>
 	result_type
 	operator()(_UniformRandomNumberGenerator& __urng)
-	{ return this->operator()(__urng, this->param()); }
+	{ return 2 * _M_gd(__urng); }
 
       template<typename _UniformRandomNumberGenerator>
 	result_type
 	operator()(_UniformRandomNumberGenerator& __urng,
-		   const param_type& __p);
+		   const param_type& __p)
+        {
+	  typedef typename std::gamma_distribution<result_type>::param_type
+	    param_type;
+	  return 2 * _M_gd(__urng, param_type(__p.n() / 2));
+	}
 
     private:
       param_type _M_param;
+
+      std::gamma_distribution<result_type> _M_gd;
     };
 
   /**
@@ -2420,12 +2585,12 @@ namespace std
       explicit
       fisher_f_distribution(_RealType __m = _RealType(1),
 			    _RealType __n = _RealType(1))
-      : _M_param(__m, __n)
+      : _M_param(__m, __n), _M_gd_x(__m / 2), _M_gd_y(__n / 2)
       { }
 
       explicit
       fisher_f_distribution(const param_type& __p)
-      : _M_param(__p)
+      : _M_param(__p), _M_gd_x(__p.m() / 2), _M_gd_y(__p.n() / 2)
       { }
 
       /**
@@ -2433,7 +2598,10 @@ namespace std
        */
       void
       reset()
-      { }
+      {
+	_M_gd_x.reset();
+	_M_gd_y.reset();
+      }
 
       /**
        *
@@ -2478,15 +2646,23 @@ namespace std
       template<typename _UniformRandomNumberGenerator>
 	result_type
 	operator()(_UniformRandomNumberGenerator& __urng)
-	{ return this->operator()(__urng, this->param()); }
+	{ return (_M_gd_x(__urng) * n()) / (_M_gd_y(__urng) * m()); }
 
       template<typename _UniformRandomNumberGenerator>
 	result_type
 	operator()(_UniformRandomNumberGenerator& __urng,
-		   const param_type& __p);
+		   const param_type& __p)
+        {
+	  typedef typename std::gamma_distribution<result_type>::param_type
+	    param_type;
+	  return ((_M_gd_x(__urng, param_type(__p.m() / 2)) * n())
+		  / (_M_gd_y(__urng, param_type(__p.n() / 2)) * m()));
+	}
 
     private:
       param_type _M_param;
+
+      std::gamma_distribution<result_type> _M_gd_x, _M_gd_y;
     };
 
   /**
@@ -2553,12 +2729,12 @@ namespace std
 
       explicit
       student_t_distribution(_RealType __n = _RealType(1))
-      : _M_param(__n), _M_nd()
+      : _M_param(__n), _M_nd(), _M_gd(__n / 2, 2)
       { }
 
       explicit
       student_t_distribution(const param_type& __p)
-      : _M_param(__p), _M_nd()
+      : _M_param(__p), _M_nd(), _M_gd(__p.n() / 2, 2)
       { }
 
       /**
@@ -2566,7 +2742,10 @@ namespace std
        */
       void
       reset()
-      { _M_nd.reset(); }
+      {
+	_M_nd.reset();
+	_M_gd.reset();
+      }
 
       /**
        *
@@ -2606,18 +2785,26 @@ namespace std
 
       template<typename _UniformRandomNumberGenerator>
 	result_type
-	operator()(_UniformRandomNumberGenerator& __urng)
-	{ return this->operator()(__urng, this->param()); }
+        operator()(_UniformRandomNumberGenerator& __urng)
+        { return _M_nd(__urng) * std::sqrt(n() / _M_gd(__urng)); }
 
       template<typename _UniformRandomNumberGenerator>
 	result_type
 	operator()(_UniformRandomNumberGenerator& __urng,
-		   const param_type& __p);
+		   const param_type& __p)
+        {
+	  typedef typename std::gamma_distribution<result_type>::param_type
+	    param_type;
+	
+	  const result_type __g = _M_gd(__urng, param_type(__p.n() / 2, 2));
+	  return _M_nd(__urng) * std::sqrt(__p.n() / __g);
+        }
 
     private:
       param_type _M_param;
 
-      normal_distribution<result_type> _M_nd;
+      std::normal_distribution<result_type> _M_nd;
+      std::gamma_distribution<result_type> _M_gd;
     };
 
   /**
@@ -2977,7 +3164,7 @@ namespace std
       param_type _M_param;
 
       // NB: Unused when _GLIBCXX_USE_C99_MATH_TR1 is undefined.
-      normal_distribution<double> _M_nd;
+      std::normal_distribution<double> _M_nd;
     };
 
 
@@ -3166,12 +3353,12 @@ namespace std
 
       explicit
       negative_binomial_distribution(_IntType __k = 1, double __p = 0.5)
-      : _M_param(__k, __p)
+      : _M_param(__k, __p), _M_gd(__k, __p / (1.0 - __p))
       { }
 
       explicit
       negative_binomial_distribution(const param_type& __p)
-      : _M_param(__p)
+      : _M_param(__p), _M_gd(__p.k(), __p.p() / (1.0 - __p.p()))
       { }
 
       /**
@@ -3179,7 +3366,7 @@ namespace std
        */
       void
       reset()
-      { }
+      { _M_gd.reset(); }
 
       /**
        * @brief Return the @f$ k @f$ parameter of the distribution.
@@ -3226,8 +3413,7 @@ namespace std
 
       template<typename _UniformRandomNumberGenerator>
 	result_type
-	operator()(_UniformRandomNumberGenerator& __urng)
-	{ return this->operator()(__urng, this->param()); }
+        operator()(_UniformRandomNumberGenerator& __urng);
 
       template<typename _UniformRandomNumberGenerator>
 	result_type
@@ -3236,6 +3422,8 @@ namespace std
 
     private:
       param_type _M_param;
+
+      std::gamma_distribution<double> _M_gd;
     };
 
   /**
@@ -3421,7 +3609,7 @@ namespace std
       param_type _M_param;
 
       // NB: Unused when _GLIBCXX_USE_C99_MATH_TR1 is undefined.
-      normal_distribution<double> _M_nd;
+      std::normal_distribution<double> _M_nd;
     };
 
   /**
@@ -3575,164 +3763,6 @@ namespace std
 
 
   /**
-   * @brief A gamma continuous distribution for random numbers.
-   *
-   * The formula for the gamma probability density function is
-   * @f$ p(x|\alpha,\beta) = \frac{1}{\beta\Gamma(\alpha)}
-   *                         (x/\beta)^{\alpha - 1} e^{-x/\beta} @f$.
-   */
-  template<typename _RealType = double>
-    class gamma_distribution
-    {
-    public:
-      /** The type of the range of the distribution. */
-      typedef _RealType result_type;
-      /** Parameter type. */
-      struct param_type
-      {
-	typedef gamma_distribution<_RealType> distribution_type;
-	friend class gamma_distribution<_RealType>;
-
-	explicit
-	param_type(_RealType __alpha_val = _RealType(1),
-		   _RealType __beta_val = _RealType(1))
-	: _M_alpha(__alpha_val), _M_beta(__beta_val)
-	{
-	  _GLIBCXX_DEBUG_ASSERT(_M_alpha > _RealType(0));
-	  _M_initialize();
-	}
-
-	_RealType
-	alpha() const
-	{ return _M_alpha; }
-
-	_RealType
-	beta() const
-	{ return _M_beta; }
-
-      private:
-	void
-	_M_initialize();
-
-	_RealType _M_alpha;
-	_RealType _M_beta;
-
-	_RealType _M_malpha, _M_a2;
-      };
-
-    public:
-      /**
-       * @brief Constructs a gamma distribution with parameters
-       * @f$ \alpha @f$ and @f$ \beta @f$.
-       */
-      explicit
-      gamma_distribution(_RealType __alpha_val = _RealType(1),
-			 _RealType __beta_val = _RealType(1))
-      : _M_param(__alpha_val, __beta_val), _M_nd()
-      { }
-
-      explicit
-      gamma_distribution(const param_type& __p)
-      : _M_param(__p), _M_nd()
-      { }
-
-      /**
-       * @brief Resets the distribution state.
-       */
-      void
-      reset()
-      { _M_nd.reset(); }
-
-      /**
-       * @brief Returns the @f$ \alpha @f$ of the distribution.
-       */
-      _RealType
-      alpha() const
-      { return _M_param.alpha(); }
-
-      /**
-       * @brief Returns the @f$ \beta @f$ of the distribution.
-       */
-      _RealType
-      beta() const
-      { return _M_param.beta(); }
-
-      /**
-       * @brief Returns the parameter set of the distribution.
-       */
-      param_type
-      param() const
-      { return _M_param; }
-
-      /**
-       * @brief Sets the parameter set of the distribution.
-       * @param __param The new parameter set of the distribution.
-       */
-      void
-      param(const param_type& __param)
-      { _M_param = __param; }
-
-      /**
-       * @brief Returns the greatest lower bound value of the distribution.
-       */
-      result_type
-      min() const
-      { return result_type(0); }
-
-      /**
-       * @brief Returns the least upper bound value of the distribution.
-       */
-      result_type
-      max() const
-      { return std::numeric_limits<result_type>::max(); }
-
-      template<typename _UniformRandomNumberGenerator>
-	result_type
-	operator()(_UniformRandomNumberGenerator& __urng)
-	{ return this->operator()(__urng, this->param()); }
-
-      template<typename _UniformRandomNumberGenerator>
-	result_type
-	operator()(_UniformRandomNumberGenerator& __urng,
-		   const param_type& __p);
-
-    private:
-      param_type _M_param;
-
-      normal_distribution<result_type> _M_nd;
-    };
-
-  /**
-   * @brief Inserts a %gamma_distribution random number distribution
-   * @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %gamma_distribution random number distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   * an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-	       const std::gamma_distribution<_RealType>&);
-
-  /**
-   * @brief Extracts a %gamma_distribution random number distribution
-   * @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x  A %gamma_distribution random number generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-	       std::gamma_distribution<_RealType>&);
-
-
-  /**
    * @brief A weibull_distribution random number distribution.
    *
    * The formula for the normal probability density function is
diff --git a/libstdc++-v3/include/bits/random.tcc b/libstdc++-v3/include/bits/random.tcc
index b933f6d..eb2ce4a 100644
--- a/libstdc++-v3/include/bits/random.tcc
+++ b/libstdc++-v3/include/bits/random.tcc
@@ -854,6 +854,20 @@ namespace std
       return __is;
     }
 
+
+  template<typename _IntType>
+    template<typename _UniformRandomNumberGenerator>
+      typename negative_binomial_distribution<_IntType>::result_type
+      negative_binomial_distribution<_IntType>::
+      operator()(_UniformRandomNumberGenerator& __urng)
+      {
+	const double __y = _M_gd(__urng);
+
+	// XXX Is the constructor too slow?
+	std::poisson_distribution<result_type> __poisson(__y);
+	return __poisson(__urng);
+      }
+
   template<typename _IntType>
     template<typename _UniformRandomNumberGenerator>
       typename negative_binomial_distribution<_IntType>::result_type
@@ -861,11 +875,13 @@ namespace std
       operator()(_UniformRandomNumberGenerator& __urng,
 		 const param_type& __p)
       {
-	gamma_distribution<> __gamma(__p.k(), 1.0);
-	double __x = __gamma(__urng);
+	typedef typename std::gamma_distribution<result_type>::param_type
+	  param_type;
+	
+	const double __y =
+	  _M_gd(__urng, param_type(__p.k(), __p.p() / (1.0 - __p.p())));
 
-	poisson_distribution<result_type> __poisson(__x * __p.p()
-						    / (1.0 - __p.p()));
+	std::poisson_distribution<result_type> __poisson(__y);
 	return __poisson(__urng);
       }
 
@@ -885,7 +901,8 @@ namespace std
       __os.fill(__os.widen(' '));
       __os.precision(std::numeric_limits<double>::digits10 + 1);
 
-      __os << __x.k() << __space << __x.p();
+      __os << __x.k() << __space << __x.p()
+	   << __space << __x._M_gd;
 
       __os.flags(__flags);
       __os.fill(__fill);
@@ -906,7 +923,7 @@ namespace std
 
       _IntType __k;
       double __p;
-      __is >> __k >> __p;
+      __is >> __k >> __p >> __x._M_gd;
       __x.param(typename negative_binomial_distribution<_IntType>::
 		param_type(__k, __p));
 
@@ -1538,17 +1555,6 @@ namespace std
     }
 
 
-  template<typename _RealType>
-    template<typename _UniformRandomNumberGenerator>
-      typename chi_squared_distribution<_RealType>::result_type
-      chi_squared_distribution<_RealType>::
-      operator()(_UniformRandomNumberGenerator& __urng,
-		 const param_type& __p)
-      {
-	gamma_distribution<_RealType> __gamma(__p.n() / 2, 1.0);
-	return 2 * __gamma(__urng);
-      }
-
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
     operator<<(std::basic_ostream<_CharT, _Traits>& __os,
@@ -1565,7 +1571,7 @@ namespace std
       __os.fill(__space);
       __os.precision(std::numeric_limits<_RealType>::digits10 + 1);
 
-      __os << __x.n();
+      __os << __x.n() << __space << __x._M_gd;
 
       __os.flags(__flags);
       __os.fill(__fill);
@@ -1585,7 +1591,7 @@ namespace std
       __is.flags(__ios_base::dec | __ios_base::skipws);
 
       _RealType __n;
-      __is >> __n;
+      __is >> __n >> __x._M_gd;
       __x.param(typename chi_squared_distribution<_RealType>::
 		param_type(__n));
 
@@ -1657,23 +1663,6 @@ namespace std
     }
 
 
-  template<typename _RealType>
-    template<typename _UniformRandomNumberGenerator>
-      typename fisher_f_distribution<_RealType>::result_type
-      fisher_f_distribution<_RealType>::
-      operator()(_UniformRandomNumberGenerator& __urng,
-		 const param_type& __p)
-      {
-	gamma_distribution<_RealType> __gamma;
-	_RealType __ym = __gamma(__urng,
-	 typename gamma_distribution<_RealType>::param_type(__p.m() / 2, 2));
-
-	_RealType __yn = __gamma(__urng,
-	 typename gamma_distribution<_RealType>::param_type(__p.n() / 2, 2));
-
-	return (__ym * __p.n()) / (__yn * __p.m());
-      }
-
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
     operator<<(std::basic_ostream<_CharT, _Traits>& __os,
@@ -1690,7 +1679,8 @@ namespace std
       __os.fill(__space);
       __os.precision(std::numeric_limits<_RealType>::digits10 + 1);
 
-      __os << __x.m() << __space << __x.n();
+      __os << __x.m() << __space << __x.n()
+	   << __space << __x._M_gd_x << __space << __x._M_gd_y;
 
       __os.flags(__flags);
       __os.fill(__fill);
@@ -1710,7 +1700,7 @@ namespace std
       __is.flags(__ios_base::dec | __ios_base::skipws);
 
       _RealType __m, __n;
-      __is >> __m >> __n;
+      __is >> __m >> __n >> __x._M_gd_x >> __x._M_gd_y;
       __x.param(typename fisher_f_distribution<_RealType>::
 		param_type(__m, __n));
 
@@ -1719,43 +1709,6 @@ namespace std
     }
 
 
-  template<typename _RealType>
-    template<typename _UniformRandomNumberGenerator>
-      typename student_t_distribution<_RealType>::result_type
-      student_t_distribution<_RealType>::
-      operator()(_UniformRandomNumberGenerator& __urng,
-		 const param_type& __param)
-      {
-	if (__param.n() <= 2.0)
-	  {
-	    _RealType __y1 = _M_nd(__urng);
-	    chi_squared_distribution<_RealType> __chisq(__param.n());
-	    _RealType __y2 = __chisq(__urng);
-
-	    return __y1 / std::sqrt(__y2 / __param.n());
-	  }
-	else
-	  {
-	    _RealType __y1, __y2, __z;
-	    exponential_distribution<_RealType>
-	      __exponential(1.0 / (__param.n() / 2.0 - 1.0));
-
-	    do
-	      {
-		__y1 = _M_nd(__urng);
-		__y2 = __exponential(__urng);
-
-		__z = __y1 * __y1 / (__param.n() - 2.0);
-	      }
-	    while (1.0 - __z < 0.0 || std::exp(-__y2 - __z) > (1.0 - __z));
-
-	    // Note that there is a typo in Knuth's formula, the line below
-	    // is taken from the original paper of Marsaglia, Mathematics of
-	    // Computation, 34 (1980), p 234-256
-	    return __y1 / std::sqrt((1.0 - 2.0 / __param.n()) * (1.0 - __z));
-	  }
-      }
-
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
     operator<<(std::basic_ostream<_CharT, _Traits>& __os,
@@ -1772,7 +1725,7 @@ namespace std
       __os.fill(__space);
       __os.precision(std::numeric_limits<_RealType>::digits10 + 1);
 
-      __os << __x.n() << __space << __x._M_nd;
+      __os << __x.n() << __space << __x._M_nd << __space << __x._M_gd;
 
       __os.flags(__flags);
       __os.fill(__fill);
@@ -1792,7 +1745,7 @@ namespace std
       __is.flags(__ios_base::dec | __ios_base::skipws);
 
       _RealType __n;
-      __is >> __n >> __x._M_nd;
+      __is >> __n >> __x._M_nd >> __x._M_gd;
       __x.param(typename student_t_distribution<_RealType>::param_type(__n));
 
       __is.flags(__flags);