CRNLinearInterpolation.cpp

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/* Copyright 2012-2016 CoReNum, ENS-Lyon
 * 
 * This file is part of libcrn.
 * 
 * libcrn is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * libcrn is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with libcrn.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * file: CRNLinearInterpolation.cpp
 * \author Yann LEYDIER
 */

#include <CRNMath/CRNLinearInterpolation.h>
#include <CRNData/CRNDataFactory.h>
#include <CRNi18n.h>

using namespace crn;

double LinearInterpolation::operator[](double x) const
{
    double slope, x0, y0;
    if (x < data.front().X)
    {
        x0 = data[0].X;
        y0 = data[0].Y;
        slope = (data[1].Y - y0) / (data[1].X - x0);
    }
    if (x > data.back().X)
    {
        x0 = data.back().X;
        y0 = data.back().Y;
        slope = (data[data.size() - 2].Y - y0) / (data[data.size() - 2].X - x0);
    }
    else
    {
        for (size_t tmp = 0; tmp < data.size() - 1; ++tmp)
        {
            if (data[tmp].X == x)
                return data[tmp].Y;
            else if ((data[tmp].X <= x) && (data[tmp + 1].X >= x))
            {
                x0 = data[tmp].X;
                y0 = data[tmp].Y;
                slope = (data[tmp + 1].Y - y0) / (data[tmp + 1].X - x0);
                break;
            }
        }
    }
    return y0 + slope * (x - x0);
}

void LinearInterpolation::Deserialize(xml::Element &el)
{
    if (el.GetName() != "LinearInterpolation")
    {
        throw ExceptionInvalidArgument(StringUTF8("void LinearInterpolation::Deserialize(xml::Element &el): ") + 
                _("Wrong XML element."));
    }

    std::vector<crn::Point2DDouble> newdata;
    for (xml::Element sel = el.BeginElement(); sel != el.EndElement(); ++sel)
    {
        newdata.push_back(Point2DDouble());
        newdata.back().Deserialize(sel); // may throw
    }
    data.swap(newdata);
}

xml::Element LinearInterpolation::Serialize(xml::Element &parent) const
{
    xml::Element el(parent.PushBackElement("LinearInterpolation"));

    for (const Point2DDouble &p : data)
        p.Serialize(el);

    return el;
}

CRN_BEGIN_CLASS_CONSTRUCTOR(LinearInterpolation)
    CRN_DATA_FACTORY_REGISTER(U"LinearInterpolation", LinearInterpolation)
    Cloner::Register<LinearInterpolation>();
CRN_END_CLASS_CONSTRUCTOR(LinearInterpolation)