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- /*
- * Copyright (C) 2021 Christopher J. Howard
- *
- * This file is part of Antkeeper source code.
- *
- * Antkeeper source code 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.
- *
- * Antkeeper source code 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 Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
- */
-
- #ifndef ANTKEEPER_PHYSICS_LIGHT_PHOTOMETRY_HPP
- #define ANTKEEPER_PHYSICS_LIGHT_PHOTOMETRY_HPP
-
- #include "math/constants.hpp"
- #include "math/quadrature.hpp"
-
- namespace physics {
- namespace light {
-
- /**
- * Calculates the luminous efficiency of a light source.
- *
- * @param spd Unary function object that returns spectral radiance given a wavelength.
- * @param lef Unary function object that returns luminous efficiency given a wavelength.
- * @param first,last Range of sample wavelengths.
- * @return Luminous efficiency, on `[0, 1]`.
- *
- * @see physics::light::blackbody::spectral_radiance
- * @see physics::light::luminosity::photopic
- */
- template <class T, class UnaryOp1, class UnaryOp2, class InputIt>
- T luminous_efficiency(UnaryOp1 spd, UnaryOp2 lef, InputIt first, InputIt last)
- {
- auto spd_lef = [spd, lef](T x) -> T
- {
- return spd(x) * lef(x);
- };
-
- const T num = math::quadrature::trapezoid(spd_lef, first, last);
- const T den = math::quadrature::trapezoid(spd, first, last);
-
- return num / den;
- }
-
- /**
- * Calculates luminous efficacy given luminous efficiency.
- *
- * @param efficiency Luminous efficiency, on `[0, 1]`.
- * @return Luminous flux, in lumens.
- */
- template <class T>
- T luminous_efficacy(T efficiency)
- {
- return T(683.002) * efficiency;
- }
-
- /**
- * Converts watts (radiant flux) to lumens (luminous flux).
- *
- * @param radient_flux Radiance flux, in watts.
- * @param efficiency Luminous efficiency, on `[0, 1]`.
- * @return Luminous flux, in lumens.
- */
- template <class T>
- T watts_to_lumens(T radient_flux, T efficiency)
- {
- return radient_flux * luminous_efficacy(efficiency);
- }
-
- } // namespace light
- } // namespace physics
-
- #endif // ANTKEEPER_PHYSICS_LIGHT_PHOTOMETRY_HPP
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