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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
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