make_lin_space.hpp

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/*
 * Copyright (C) 2019-2022 The ESPResSo project
 *
 * This file is part of ESPResSo.
 *
 * ESPResSo 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 of the License, or
 * (at your option) any later version.
 *
 * ESPResSo 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, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef UTILS_MAKE_LIN_SPACE_HPP
#define UTILS_MAKE_LIN_SPACE_HPP
 
#include <boost/iterator/counting_iterator.hpp>
#include <boost/iterator/transform_iterator.hpp>
#include <boost/range/iterator_range.hpp>
 
#include <cstddef>
 
namespace Utils {
/**
 * @brief Equally spaced values in interval
 *
 * Returns a range of equally spaced values in
 * the range of start and stop, like numpy.linspace.
 *
 * @tparam T floating point type
 * @param start Start value of the interval
 * @param stop End value of the interval
 * @param number Number of partition points
 * @param endpoint If true, the last point is
 *        stop, otherwise one less.
 * @return Range of equally spaced values
 */
template <class T>
auto make_lin_space(T start, T stop, std::size_t number, bool endpoint = true) {
  using boost::make_counting_iterator;
  using boost::make_iterator_range;
  using boost::make_transform_iterator;
 
  auto const dx = (stop - start) / T(number - endpoint);
  auto x = [dx, start](std::size_t i) { return start + T(i) * dx; };
 
  return make_iterator_range(
      make_transform_iterator(make_counting_iterator(std::size_t(0)), x),
      make_transform_iterator(make_counting_iterator(number), x));
}
} // namespace Utils
 
#endif