Scaling1d.h

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// -*- LSST-C++ -*-
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#ifndef LSST_AFW_MATH_POLYNOMIALS_Scaling1d_h_INCLUDED
#define LSST_AFW_MATH_POLYNOMIALS_Scaling1d_h_INCLUDED
 
 
namespace lsst { namespace geom { namespace polynomials {

class Scaling1d {
public:

    Scaling1d(double scale, double shift) noexcept:
        _scale(scale),
        _shift(shift)
    {}

    Scaling1d(Scaling1d const &) noexcept = default;

    Scaling1d(Scaling1d &&) noexcept = default;

    Scaling1d & operator=(Scaling1d const &) noexcept = default;

    Scaling1d & operator=(Scaling1d &&) noexcept = default;

    double applyForward(double x) const noexcept {
        return (x + getShift())*getScale();
    }

    double applyInverse(double y) const noexcept {
        return y/_scale - _shift;
    }

    double getScale() const noexcept { return _scale; }

    double getShift() const noexcept { return _shift; }

    Scaling1d inverted() const noexcept {
        return Scaling1d(1.0/_scale, -_shift*_scale);
    }

    Scaling1d then(Scaling1d const & second) const noexcept {
        return Scaling1d(getScale()*second.getScale(),
                                 getShift() + second.getShift()/getScale());
    }
 
private:
    double _scale;
    double _shift;
};

inline Scaling1d makeUnitRangeScaling1d(double min, double max) noexcept {
    return Scaling1d(2.0/(max - min), -0.5*(min + max));
}
 
}}} // namespace lsst::geom::polynomials
 
#endif // !LSST_AFW_MATH_POLYNOMIALS_Scaling1d_h_INCLUDED