env/ceres-solver/include/ceres/constants.h

// Ceres Solver - A fast non-linear least squares minimizer
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// http://ceres-solver.org/
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// Author: hellston20a@gmail.com (H S Helson Go)

#ifndef CERES_PUBLIC_CONSTANTS_H_
#define CERES_PUBLIC_CONSTANTS_H_

// TODO(HSHelson): This header should no longer be necessary once C++20's
// <numbers> (e.g. std::numbers::pi_v) becomes usable
namespace ceres::constants {
template <typename T>
inline constexpr T pi_v(3.141592653589793238462643383279502884);
}  // namespace ceres::constants

#endif  // CERES_PUBLIC_CONSTANTS_H_