angle_util.hh

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/*
  Masala
  Copyright (C) 2025 Vikram K. Mulligan
 
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU Affero General Public License as published by
  the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 
  You should have received a copy of the GNU Affero General Public License
  along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
 
/// @file src/numeric_api/utility/angles/angle_util.hh
/// @brief Inlined functions for manipulating angles.
/// @author Vikram K. Mulligan (vmulligan@flatironinstitute.org).
 
#ifndef Masala_src_numeric_api_utility_angles_angle_util_hh
#define Masala_src_numeric_api_utility_angles_angle_util_hh
 
#include <cmath>
 
namespace masala {
namespace numeric_api {
namespace utility {
namespace angles {
 
    /// @brief Convert an angle, in degrees, to the equivalent angle, in degrees, in the range [0, 360).
    /// @tparam T The type of the angle (e.g. float, double, masala::base::Real).
    /// @param angle_in The input angle, in degrees.
    /// @return An angle, in degrees, in the range [0, 360).
    template < typename T >
    inline
    T
    positive_angle_degrees(
        T angle_in
    ) {
        T const fmod_result( std::fmod( angle_in, T(360) ) );
        return (fmod_result < 0 ? fmod_result + T(360) : fmod_result);
    }
 
    /// @brief Convert an angle, in degrees, to the equivalent angle, in degrees, in the range [-180, 180).
    /// @tparam T The type of the angle (e.g. float, double, masala::base::Real).
    /// @param angle_in The input angle, in degrees.
    /// @return An angle, in degrees, in the range [-180, 180).
    template < typename T >
    inline
    T
    zero_centred_angle_degrees(
        T angle_in
    ) {
        return ( positive_angle_degrees( angle_in + T(180) ) - T(180) );
    }
 
} // namespace angles
} // namespace utility
} // namespace numeric_api
} // namespace masala
 
#endif // Masala_src_numeric_api_utility_angles_angle_util_hh