lsst::afw::math::InterpolateConstant Class Reference

Inheritance diagram for lsst::afw::math::InterpolateConstant:

Public Member Functions
virtual	~InterpolateConstant ()
virtual double	interpolate (double const x) const
	Interpolate a constant to the point xInterp. More...
Public Member Functions inherited from lsst::afw::math::Interpolate
virtual	~Interpolate ()

Private Member Functions
	InterpolateConstant (std::vector< double > const &x, std::vector< double > const &y, Interpolate::Style const style)

Private Attributes
std::vector< double > ::const_iterator	_old

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

Additional Inherited Members
Public Types inherited from lsst::afw::math::Interpolate
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 }
Protected Member Functions inherited from lsst::afw::math::Interpolate
	Interpolate (std::vector< double > const &x, std::vector< double > const &y, Interpolate::Style const style=UNKNOWN)
	Interpolate (std::pair< std::vector< double >, std::vector< double > > const xy, Interpolate::Style const style=UNKNOWN)
Protected Attributes inherited from lsst::afw::math::Interpolate
std::vector< double > const	_x
std::vector< double > const	_y
Interpolate::Style const	_style

Detailed Description

Definition at line 82 of file Interpolate.cc.

Constructor & Destructor Documentation

virtual lsst::afw::math::InterpolateConstant::~InterpolateConstant ( )

inlinevirtual

Definition at line 86 of file Interpolate.cc.

{}

lsst::afw::math::InterpolateConstant::InterpolateConstant ( std::vector< double > const &  x, std::vector< double > const &  y, Interpolate::Style const  style  )

inlineprivate

Parameters

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

Definition at line 89 of file Interpolate.cc.

                         :
        Interpolate(recenter(x, y)), _old(_x.begin()) {}

Member Function Documentation

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

virtual

Interpolate a constant to the point xInterp.

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

Definition at line 99 of file Interpolate.cc.

{
    //
    // Look for the interval wherein lies xInterp.  We could naively use std::upper_bound, but that requires a
    // logarithmic time lookup so we'll cache the previous answer in _old -- this is a good idea if people
    // usually call this routine repeatedly for a range of x
    //
    // We start by searching up from _old
    //
    if (xInterp < *_old) {              // We're to the left of the cache
        if (_old == _x.begin()) {       // ... actually off the array
            return _y[0];
        }
        _old = _x.begin();              // reset the cached point to the start of the array
    } else {                            // see if we're still in the same interval
        if (_old < _x.end() - 1 and xInterp < *(_old + 1)) { // we are, so we're done
            return _y[_old - _x.begin()];
        }
    }
    // We're to the right of the cached point and not in the same inverval, so search up from _old
    std::vector<double>::const_iterator low = std::upper_bound(_old, _x.end(), xInterp);
    //
    // Did that work?
    if (low == _old && _old != _x.begin()) {
        // No.  Sigh.  Search the entire range.
        low = std::upper_bound(_x.begin(), low + 1, xInterp);
    }
    //
    // OK, we've found the right interval.  Return the desired value, being careful at the ends
    //
    if (low == _x.end()) {
        return _y[_y.size() - 1];
    } else if (low == _x.begin()) {
        return _y[0];
    } else {
        --low;
        _old = low;
        return _y[low - _x.begin()];
    }
}

Friends And Related Function Documentation

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

friend

A factory function to make Interpolate objects

Member Data Documentation

std::vector<double>::const_iterator lsst::afw::math::InterpolateConstant::_old

mutableprivate

Definition at line 94 of file Interpolate.cc.

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

• /home/lsstsw/stack/Linux64/afw/11.0-2-g04d2804/src/math/Interpolate.cc