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/* This file is part of the OpenLB library
*
* Copyright (C) 2017 Adrian Kummerlaender
* E-mail contact: info@openlb.net
* The most recent release of OpenLB can be downloaded at
* <http://www.openlb.net/>
*
* This program 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 2
* of the License, or (at your option) any later version.
*
* This program 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 program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifndef UTILITY_ARITHMETIC_H
#define UTILITY_ARITHMETIC_H
#include <cmath>
#include <functional>
namespace olb {
namespace util {
/// Wrapper of function object std::minus with special handling for bool
/**
* \tparam T Domain of the substraction operation, _without_ operation is
* performed for boolean inputs.
*
* Note that specialization is not required for boolean union (add) and
* intersection (multiply) functors as their behavior is implicitly defined
* by the corresponding arithmetic operation on the integer representation.
**/
template <typename T>
struct minus {
/// symbol character for functor naming
static const char symbol = '-';
constexpr T operator() (const T& lhs, const T& rhs) const
{
return std::minus<T>()(lhs, rhs);
}
};
/// Operator specialization for boolean _without_ operation
/**
* i.e. implements what one reasonably expects to happen when substracting
* indicator functors.
**/
template <>
constexpr bool minus<bool>::operator() (const bool& lhs, const bool& rhs) const
{
return lhs && !rhs;
}
/// Wrapper of function object std::plus
template <typename T>
struct plus : public std::plus<T> {
/// symbol character for functor naming
static const char symbol = '+';
};
/// Wrapper of function object std::multiplies
template <typename T>
struct multiplies : public std::multiplies<T> {
/// symbol character for functor naming
static const char symbol = '*';
};
/// Wrapper of function object std::divides
template <typename T>
struct divides : public std::divides<T> {
/// symbol character for functor naming
static const char symbol = '/';
};
/// Power function object
template <typename T>
struct power {
/// symbol character for functor naming
static const char symbol = '^';
constexpr T operator() (const T& base, const T& exponent) const
{
return pow(base, exponent);
}
};
} // end namespace util
} // end namespace olb
#endif
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