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diff --git a/libstdc++-v3/testsuite/util/statistic/sample_variance.hpp b/libstdc++-v3/testsuite/util/statistic/sample_variance.hpp
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+// -*- C++ -*-
+
+// Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+
+// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
+
+// Permission to use, copy, modify, sell, and distribute this software
+// is hereby granted without fee, provided that the above copyright
+// notice appears in all copies, and that both that copyright notice
+// and this permission notice appear in supporting documentation. None
+// of the above authors, nor IBM Haifa Research Laboratories, make any
+// representation about the suitability of this software for any
+// purpose. It is provided "as is" without express or implied
+// warranty.
+
+/**
+ * @file sample_variance.hpp
+ * Contains a function for calculating a sample variance
+ */
+
+#ifndef PB_DS_SAMPLE_VAR_HPP
+#define PB_DS_SAMPLE_VAR_HPP
+
+#include <list>
+#include <numeric>
+#include <math.h>
+#include <iterator>
+
+namespace __gnu_pbds
+{
+  namespace test
+  {
+    namespace detail
+    {
+#define PB_DS_VTYPE typename std::iterator_traits<It>::value_type
+
+      template<typename It>
+      PB_DS_VTYPE
+      sample_variance(It b, It e, PB_DS_VTYPE sm)
+      {
+	PB_DS_VTYPE ss = 0;
+	size_t num_res = 0;
+
+	while (b != e)
+	  {
+	    const PB_DS_VTYPE d =* b - sm;
+	    ss += d*  d;
+	    ++num_res;
+	    ++b;
+	  }
+
+	if (num_res == 1)
+	  return 0;
+
+	return ::sqrt(ss / (num_res - 1));
+      }
+
+#undef PB_DS_VTYPE
+
+    } // namespace detail
+  } // namespace test
+} // namespace __gnu_pbds
+
+#endif 
+