normalize_angle.h

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// Ceres Solver - A fast non-linear least squares minimizer
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// Author: vitus@google.com (Michael Vitus)

#ifndef CERES_EXAMPLES_POSE_GRAPH_2D_NORMALIZE_ANGLE_H_
#define CERES_EXAMPLES_POSE_GRAPH_2D_NORMALIZE_ANGLE_H_

#include <cmath>

#include "ceres/ceres.h"

namespace ceres {

#if not(CERES_VERSION_MAJOR > 1 || (CERES_VERSION_MAJOR == 1 && CERES_VERSION_MINOR >= 12))
inline double floor   (double x) { return std::floor(x);    }

// The floor function should be used with extreme care as this operation will
// result in a zero derivative which provides no information to the solver.
//
// floor(a + h) ~= floor(a) + 0
template <typename T, int N> inline
Jet<T, N> floor(const Jet<T, N>& f) {
  return Jet<T, N>(floor(f.a));
}
#endif

namespace examples {

// Normalizes the angle in radians between [-pi and pi).
template <typename T>
inline T NormalizeAngle(const T& angle_radians) {
  // Use ceres::floor because it is specialized for double and Jet types.
  T two_pi(2.0 * M_PI);
  return angle_radians -
      two_pi * ceres::floor((angle_radians + T(M_PI)) / two_pi);
}

}  // namespace examples
}  // namespace ceres

#endif  // CERES_EXAMPLES_POSE_GRAPH_2D_NORMALIZE_ANGLE_H_