ChebyshevBoundedField.h

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// -*- LSST-C++ -*-
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#ifndef LSST_AFW_MATH_ChebyshevBoundedField_h_INCLUDED
#define LSST_AFW_MATH_ChebyshevBoundedField_h_INCLUDED

#include "ndarray.h"

#include "lsst/pex/config.h"
#include "lsst/afw/geom/AffineTransform.h"
#include "lsst/afw/math/BoundedField.h"

namespace lsst { namespace afw { namespace math {

class ChebyshevBoundedFieldControl {
public:

    ChebyshevBoundedFieldControl() : orderX(2), orderY(2), triangular(true) {}

    LSST_CONTROL_FIELD(orderX, int, "maximum Chebyshev function order in x");

    LSST_CONTROL_FIELD(orderY, int, "maximum Chebyshev function order in y");

    LSST_CONTROL_FIELD(
        triangular, bool,
        "if true, only include terms where the sum of the x and y order "
        "is less than or equal to max(orderX, orderY)"
    );

    int computeSize() const;

};

class ChebyshevBoundedField :
        public table::io::PersistableFacade<ChebyshevBoundedField>,
        public BoundedField
{
public:

    typedef ChebyshevBoundedFieldControl Control;

    ChebyshevBoundedField(
        afw::geom::Box2I const & bbox,
        ndarray::Array<double const,2,2> const & coefficients
    );

    static PTR(ChebyshevBoundedField) fit(
        afw::geom::Box2I const & bbox,
        ndarray::Array<double const,1> const & x,
        ndarray::Array<double const,1> const & y,
        ndarray::Array<double const,1> const & z,
        Control const & ctrl
    );

    static PTR(ChebyshevBoundedField) fit(
        afw::geom::Box2I const & bbox,
        ndarray::Array<double const,1> const & x,
        ndarray::Array<double const,1> const & y,
        ndarray::Array<double const,1> const & z,
        ndarray::Array<double const,1> const & w,
        Control const & ctrl
    );

    template <typename T>
    static PTR(ChebyshevBoundedField) fit(
        image::Image<T> const & image,
        Control const & ctrl
    );

    ndarray::Array<double const,2,2> getCoefficients() const { return _coefficients; }

    PTR(ChebyshevBoundedField) truncate(Control const & ctrl) const;

    PTR(ChebyshevBoundedField) relocate(geom::Box2I const & bbox) const;

    virtual double evaluate(geom::Point2D const & position) const;

    using BoundedField::evaluate;

    virtual bool isPersistable() const { return true; }

    virtual PTR(BoundedField) operator*(double const scale) const;

protected:

    virtual std::string getPersistenceName() const;

    virtual std::string getPythonModule() const;

    virtual void write(OutputArchiveHandle & handle) const;

private:

    // Internal constructor for fit() routines: just initializes the transform,
    // leaves coefficients empty.
    explicit ChebyshevBoundedField(afw::geom::Box2I const & bbox);

    geom::AffineTransform _toChebyshevRange; // maps points from the bbox to [-1,1]x[-1,1]
    ndarray::Array<double const,2,2> _coefficients;  // shape=(orderY+1, orderX+1)
};


}}} // namespace lsst::afw::math

#endif // !LSST_AFW_MATH_ChebyshevBoundedField_h_INCLUDED