lsst::afw::math::InterpolateGsl Class Reference

Inheritance diagram for lsst::afw::math::InterpolateGsl:

Public Types
enum	Style {   UNKNOWN = -1 , CONSTANT = 0 , LINEAR = 1 , NATURAL_SPLINE = 2 ,   CUBIC_SPLINE = 3 , CUBIC_SPLINE_PERIODIC = 4 , AKIMA_SPLINE = 5 , AKIMA_SPLINE_PERIODIC = 6 ,   NUM_STYLES }

Public Member Functions
	~InterpolateGsl () override
double	interpolate (double const x) const override
std::vector< double >	interpolate (std::vector< double > const &x) const
ndarray::Array< double, 1 >	interpolate (ndarray::Array< double const, 1 > const &x) const

Protected Attributes
std::vector< double > const	_x
std::vector< double > const	_y
Interpolate::Style const	_style

Friends
std::shared_ptr< Interpolate >	makeInterpolate (std::vector< double > const &x, std::vector< double > const &y, Interpolate::Style const style=Interpolate::AKIMA_SPLINE)
	A factory function to make Interpolate objects.

Detailed Description

Definition at line 170 of file Interpolate.cc.

Member Enumeration Documentation

Style

enum lsst::afw::math::Interpolate::Style

inherited

Enumerator
UNKNOWN
CONSTANT
LINEAR
NATURAL_SPLINE
CUBIC_SPLINE
CUBIC_SPLINE_PERIODIC
AKIMA_SPLINE
AKIMA_SPLINE_PERIODIC
NUM_STYLES

Definition at line 38 of file Interpolate.h.

               {
        UNKNOWN = -1,
        CONSTANT = 0,
        LINEAR = 1,
        NATURAL_SPLINE = 2,
        CUBIC_SPLINE = 3,
        CUBIC_SPLINE_PERIODIC = 4,
        AKIMA_SPLINE = 5,
        AKIMA_SPLINE_PERIODIC = 6,
        NUM_STYLES
    };

Constructor & Destructor Documentation

~InterpolateGsl()

lsst::afw::math::InterpolateGsl::~InterpolateGsl ( )

override

Definition at line 219 of file Interpolate.cc.

                                {
    ::gsl_interp_free(_interp);
    ::gsl_interp_accel_free(_acc);
}

Member Function Documentation

interpolate() [1/3]

ndarray::Array< double, 1 > lsst::afw::math::Interpolate::interpolate ( ndarray::Array< double const, 1 > const & x ) const

inherited

Definition at line 308 of file Interpolate.cc.

                                                                                             {
    int const num = x.getShape()[0];
    ndarray::Array<double, 1> out = ndarray::allocate(ndarray::makeVector(num));
    for (int i = 0; i < num; ++i) {
        std::cout << "Interpolating " << x[i] << std::endl;
        out[i] = interpolate(x[i]);
    }
    return out;
}

interpolate() [2/3]

std::vector< double > lsst::afw::math::Interpolate::interpolate ( std::vector< double > const & x ) const

inherited

Definition at line 299 of file Interpolate.cc.

                                                                           {
    size_t const num = x.size();
    std::vector<double> out(num);
    for (size_t i = 0; i < num; ++i) {
        out[i] = interpolate(x[i]);
    }
    return out;
}

interpolate() [3/3]

double lsst::afw::math::InterpolateGsl::interpolate ( double const x ) const

overridevirtual

Implements lsst::afw::math::Interpolate.

Definition at line 224 of file Interpolate.cc.

                                                             {
    // NaNs interpolate as NaN.
    if (std::isnan(xInterp)) {
        return xInterp;
    }
    // New GSL versions refuse to extrapolate.
    // gsl_interp_init() requires x to be ordered, so can just check
    // the array endpoints for out-of-bounds.
    if ((xInterp < _x.front() || (xInterp > _x.back()))) {
        // do our own quadratic extrapolation.
        // (GSL only provides first and second derivative functions)
        /* could also just fail via:
         throw LSST_EXCEPT(
         pex::exceptions::InvalidParameterError,
         (boost::format("Interpolation point %f outside range [%f, %f]")
         % x % _x.front() % _x.back()).str()
         );
         */
        double x0, y0;
        if (xInterp < _x.front()) {
            x0 = _x.front();
            y0 = _y.front();
        } else {
            x0 = _x.back();
            y0 = _y.back();
        }
        // first derivative at endpoint
        double d = ::gsl_interp_eval_deriv(_interp, &_x[0], &_y[0], x0, _acc);
        // second derivative at endpoint
        double d2 = ::gsl_interp_eval_deriv2(_interp, &_x[0], &_y[0], x0, _acc);
        return y0 + (xInterp - x0) * d + 0.5 * (xInterp - x0) * (xInterp - x0) * d2;
    }
    assert(xInterp >= _x.front());
    assert(xInterp <= _x.back());
    return ::gsl_interp_eval(_interp, &_x[0], &_y[0], xInterp, _acc);
}

Friends And Related Symbol Documentation

makeInterpolate

std::shared_ptr< Interpolate > makeInterpolate ( std::vector< double > const & x, std::vector< double > const & y, Interpolate::Style const style = Interpolate::AKIMA_SPLINE )

friend

A factory function to make Interpolate objects.

Parameters

x	the x-values of points
y	the values at x[]
style	desired interpolator

Definition at line 347 of file Interpolate.cc.

                                                                           {
    switch (style) {
        case Interpolate::CONSTANT:
            return std::shared_ptr<Interpolate>(new InterpolateConstant(x, y, style));
        default:  // use GSL
            return std::shared_ptr<Interpolate>(new InterpolateGsl(x, y, style));
    }
}

Member Data Documentation

_style

Interpolate::Style const lsst::afw::math::Interpolate::_style

protectedinherited

Definition at line 85 of file Interpolate.h.

_x

std::vector<double> const lsst::afw::math::Interpolate::_x

protectedinherited

Definition at line 83 of file Interpolate.h.

_y

std::vector<double> const lsst::afw::math::Interpolate::_y

protectedinherited

Definition at line 84 of file Interpolate.h.

---

The documentation for this class was generated from the following file:

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-10.0.0/Linux64/afw/gfe73954cf8+a1301e4c20/src/math/Interpolate.cc