NormalizedAngle.h

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/*
 * LSST Data Management System
 * Copyright 2014-2015 AURA/LSST.
 *
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * This program is free software: you can redistribute it and/or modify
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 * the Free Software Foundation, either version 3 of the License, or
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 *
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 * 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.
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#ifndef LSST_SPHGEOM_NORMALIZEDANGLE_H_
#define LSST_SPHGEOM_NORMALIZEDANGLE_H_
 
 
#include <limits>
 
#include "Angle.h"
 
 
namespace lsst {
namespace sphgeom {
 
// Forward declarations
class LonLat;
class Vector3d;
 
class NormalizedAngle {
public:
    static NormalizedAngle nan() {
        return NormalizedAngle(std::numeric_limits<double>::quiet_NaN());
    }
 
    static NormalizedAngle fromDegrees(double a) {
        return NormalizedAngle(a * RAD_PER_DEG);
    }
 
    static NormalizedAngle fromRadians(double a) {
        return NormalizedAngle(a);
    }
 
    static NormalizedAngle between(NormalizedAngle const & a,
                                   NormalizedAngle const & b);
 
    static NormalizedAngle center(NormalizedAngle const & a,
                                  NormalizedAngle const & b);
 
    NormalizedAngle() = default;
 
    NormalizedAngle(NormalizedAngle const & a) = default;
 
    explicit NormalizedAngle(Angle const & a) {
        *this = NormalizedAngle(a.asRadians());
    }
 
    explicit NormalizedAngle(double a) {
        // For really large |a|, the error in this reduction can exceed 2*PI
        // (because PI is only an approximation to π).
        if (a < 0.0) {
            _a = Angle(std::fmod(a, 2.0 * PI) + 2.0 * PI);
        } else if (a > 2 * PI) {
            _a = Angle(std::fmod(a, 2.0 * PI));
        } else {
            _a = Angle(a);
        }
    }
 
    NormalizedAngle(LonLat const &, LonLat const &);
 
    NormalizedAngle(Vector3d const &, Vector3d const &);
 
    operator Angle const & () const { return _a; }
 
    // Comparison operators
    bool operator==(Angle const & a) const { return _a == a; }
    bool operator!=(Angle const & a) const { return _a != a; }
    bool operator<(Angle const & a) const { return _a < a; }
    bool operator>(Angle const & a) const { return _a > a; }
    bool operator<=(Angle const & a) const { return _a <= a; }
    bool operator>=(Angle const & a) const { return _a >= a; }
 
    // Arithmetic operators
    Angle operator-() const { return Angle(-_a); }
    Angle operator+(Angle const & a) const { return _a + a; }
    Angle operator-(Angle const & a) const { return _a - a; }
    Angle operator*(double a) const { return _a * a; }
    Angle operator/(double a) const { return _a / a; }
    double operator/(Angle const & a) const { return _a / a; }
 
    double asDegrees() const { return _a.asDegrees(); }
 
    double asRadians() const { return _a.asRadians(); }
 
    bool isNan() const { return _a.isNan(); }
 
    NormalizedAngle getAngleTo(NormalizedAngle const & a) const {
        NormalizedAngle x;
        double d = a.asRadians() - asRadians();
        x._a = Angle((d < 0.0) ? 2.0 * PI + d : d);
        return x;
    }
 
private:
    Angle _a;
};
 
inline NormalizedAngle const & abs(NormalizedAngle const & a) { return a; }
 
}} // namespace lsst::sphgeom
 
#endif // LSST_SPHGEOM_NORMALIZEDANGLE_H_