* include/ext/random.tcc (uniform_on_sphere_helper): Define.

        (uniform_on_sphere_distribution::operator()): Use the new helper
        class for the implementation.

        * testsuite/ext/random/uniform_on_sphere_distribution/operators/
        equal.cc: Remove bogus part of comment.
        * testsuite/ext/random/uniform_on_sphere_distribution/operators/
        inequal.cc: Likewise.
        * testsuite/ext/random/uniform_on_sphere_distribution/operators/
        serialize.cc: Add check to verify result of serialzation and
        deserialization.
        * testsuite/ext/random/uniform_on_sphere_distribution/operators/
        generate.cc: New file.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@213779 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 79 insertions, 12 deletions

diff --git a/libstdc++-v3/include/ext/random.tcc b/libstdc++-v3/include/ext/random.tcc
index 05361d8f491..997c204ffe2 100644
--- a/libstdc++-v3/include/ext/random.tcc
+++ b/libstdc++-v3/include/ext/random.tcc
@@ -1540,6 +1540,83 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 
 
+  namespace {
+
+    // Helper class for the uniform_on_sphere_distribution generation
+    // function.
+    template<std::size_t _Dimen, typename _RealType>
+      class uniform_on_sphere_helper
+      {
+	typedef typename uniform_on_sphere_distribution<_Dimen, _RealType>::result_type result_type;
+
+      public:
+	template<typename _NormalDistribution, typename _UniformRandomNumberGenerator>
+	result_type operator()(_NormalDistribution& __nd,
+			       _UniformRandomNumberGenerator& __urng)
+        {
+	  result_type __ret;
+	  typename result_type::value_type __norm;
+
+	  do
+	    {
+	      auto __sum = _RealType(0);
+
+	      std::generate(__ret.begin(), __ret.end(),
+			    [&__nd, &__urng, &__sum](){
+			      _RealType __t = __nd(__urng);
+			      __sum += __t * __t;
+			      return __t; });
+	      __norm = std::sqrt(__sum);
+	    }
+	  while (__norm == _RealType(0) || ! std::isfinite(__norm));
+
+	  std::transform(__ret.begin(), __ret.end(), __ret.begin(),
+			 [__norm](_RealType __val){ return __val / __norm; });
+
+	  return __ret;
+        }
+      };
+
+
+    template<typename _RealType>
+      class uniform_on_sphere_helper<2, _RealType>
+      {
+	typedef typename uniform_on_sphere_distribution<2, _RealType>::
+	  result_type result_type;
+
+      public:
+	template<typename _NormalDistribution,
+		 typename _UniformRandomNumberGenerator>
+	result_type operator()(_NormalDistribution&,
+			       _UniformRandomNumberGenerator& __urng)
+        {
+	  result_type __ret;
+	  _RealType __sq;
+	  std::__detail::_Adaptor<_UniformRandomNumberGenerator,
+				  _RealType> __aurng(__urng);
+
+	  do
+	    {
+	      __ret[0] = _RealType(2) * __aurng() - _RealType(1);
+	      __ret[1] = _RealType(2) * __aurng() - _RealType(1);
+
+	      __sq = __ret[0] * __ret[0] + __ret[1] * __ret[1];
+	    }
+	  while (__sq == _RealType(0) || __sq > _RealType(1));
+
+	  // Yes, we do not just use sqrt(__sq) because hypot() is more
+	  // accurate.
+	  auto __norm = std::hypot(__ret[0], __ret[1]);
+	  __ret[0] /= __norm;
+	  __ret[1] /= __norm;
+
+	  return __ret;
+        }
+      };
+
+  }
+
+
   template<std::size_t _Dimen, typename _RealType>
     template<typename _UniformRandomNumberGenerator>
       typename uniform_on_sphere_distribution<_Dimen, _RealType>::result_type
@@ -1547,18 +1624,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       operator()(_UniformRandomNumberGenerator& __urng,
 		 const param_type& __p)
       {
-	result_type __ret;
-	_RealType __sum = _RealType(0);
-
-	std::generate(__ret.begin(), __ret.end(),
-		      [&__urng, &__sum, this](){ _RealType __t = _M_nd(__urng);
-						 __sum += __t * __t;
-						 return __t; });
-	auto __norm = std::sqrt(__sum);
-	std::transform(__ret.begin(), __ret.end(), __ret.begin(),
-		       [__norm](_RealType __val){ return __val / __norm; });
-
-	return __ret;
+        uniform_on_sphere_helper<_Dimen, _RealType> __helper;
+        return __helper(_M_nd, __urng);
       }
 
   template<std::size_t _Dimen, typename _RealType>