constants.h

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// -*- LSST-C++ -*-

/*
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 * Copyright 2008, 2009, 2010, 2011 LSST Corporation.
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#ifndef LSST_AFW_MATH_SHAPELETS_CONSTANTS_H
#define LSST_AFW_MATH_SHAPELETS_CONSTANTS_H

#include "lsst/afw/geom/ellipses.h"
#include "ndarray.h"
#include "lsst/pex/exceptions.h"

namespace lsst { namespace shapelet {

extern double const BASIS_NORMALIZATION; 

typedef afw::geom::ellipses::Quadrupole EllipseCore;

enum BasisTypeEnum {
    HERMITE, 
    LAGUERRE, 
};

inline int computeOffset(int order) { return order * (order + 1) / 2; }

inline int computeSize(int order) { return computeOffset(order + 1); }

inline int computeOrder(int size) {
    int order = (std::sqrt(8*size + 1) - 3)/2;
    if (computeSize(order) != size) {
        throw LSST_EXCEPT(
            pex::exceptions::InvalidParameterError,
            "Invalid size for shapelet coefficient matrix"
        );
    }
    return order;
}

typedef ndarray::Array<double,1> Array1d;

inline double intSqrt(int n) {
    return std::sqrt(double(n));
}

inline double rationalSqrt(int n, int d) {
    return std::sqrt(double(n) / double(d));
}

}} // namespace lsst::shapelet

#endif // !defined(LSST_AFW_MATH_SHAPELETS_CONSTANTS_H)