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Merge pull request #3 from mspraggs/master
TabFunction: Added optional interpolation type argument
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commit
3f28430e4a
@ -18,6 +18,7 @@ noinst_PROGRAMS = \
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exCompiledDoubleFunction\
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exDerivative \
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exIntegrator \
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exInterp \
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exMat \
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exMathInterpreter \
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exPlot \
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@ -42,6 +43,10 @@ exFit_CFLAGS = -g -O2
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exFit_LDFLAGS = -L../lib/.libs -lLatAnalyze
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endif
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exInterp_SOURCES = exInterp.cpp
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exInterp_CFLAGS = -g -O2
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exInterp_LDFLAGS = -L../lib/.libs -lLatAnalyze
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exIntegrator_SOURCES = exIntegrator.cpp
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exIntegrator_CFLAGS = -g -O2
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exIntegrator_LDFLAGS = -L../lib/.libs -lLatAnalyze
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38
examples/exInterp.cpp
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38
examples/exInterp.cpp
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@ -0,0 +1,38 @@
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/*
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* TabFunction.cpp, part of LatAnalyze 3
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*
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* Copyright (C) 2013 - 2015 Antonin Portelli, Matt Spraggs
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*
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* LatAnalyze 3 is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* LatAnalyze 3 is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with LatAnalyze 3. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <LatAnalyze/TabFunction.hpp>
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int main(int argc, char* argv[])
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{
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Latan::DVec xs(3);
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xs << -1.0, 0.0, 1.0;
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Latan::DVec ys(3);
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ys << 1.0, 0.0, 1.0;
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auto tab = Latan::TabFunction(xs, ys, Latan::InterpType::QUADRATIC);
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std::cout << "Interpolating naive y = x^2 data..." << std::endl;
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for (double x = -1.0; x < 1.0; x += 0.1) {
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double y = tab(&x);
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std::cout << "y @ " << x << " = " << y;
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std::cout << " ( " << x * x << " expected)" << std::endl;
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}
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}
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@ -27,14 +27,16 @@ using namespace Latan;
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* TabFunction implementation *
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******************************************************************************/
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// constructors ////////////////////////////////////////////////////////////////
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TabFunction::TabFunction(const DVec &x, const DVec &y)
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: TabFunction()
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TabFunction::TabFunction(const DVec &x, const DVec &y,
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const InterpType interpType)
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: interpType_(interpType)
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{
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setData(x, y);
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}
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TabFunction::TabFunction(const XYStatData &data, const Index i, const Index j)
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: TabFunction()
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TabFunction::TabFunction(const XYStatData &data, const Index i, const Index j,
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const InterpType interpType)
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: interpType_(interpType)
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{
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setData(data, i, j);
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}
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@ -60,26 +62,72 @@ void TabFunction::setData(const XYStatData &data, const Index i, const Index j)
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// function call ///////////////////////////////////////////////////////////////
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double TabFunction::operator()(const double *arg) const
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{
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double x = arg[0], x_a, x_b, y_a, y_b;
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if ((x < value_.begin()->first)||(x >= value_.rbegin()->first))
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{
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LATAN_ERROR(Range, "tabulated function variable out of range (x= "
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+ strFrom(x) + " not in ["
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+ strFrom(value_.begin()->first) + ", "
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+ strFrom(value_.rbegin()->first) + "])");
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double result = 0.0, x = arg[0];
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if ((x < value_.begin()->first) || (x >= value_.rbegin()->first)) {
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LATAN_ERROR(Range, "tabulated function variable out of range "
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"(x= " + strFrom(x) + " not in ["
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+ strFrom(value_.begin()->first) + ", "
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+ strFrom(value_.rbegin()->first) + "])");
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}
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auto i = value_.equal_range(x);
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auto low = (x == i.first->first) ? i.first : prev(i.first);
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auto high = i.second;
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switch (interpType_) {
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case InterpType::LINEAR: {
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double x_a, x_b, y_a, y_b;
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x_a = low->first;
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x_b = high->first;
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y_a = low->second;
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y_b = high->second;
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result = y_a + (x - x_a) * (y_b - y_a) / (x_b - x_a);
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break;
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}
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case InterpType::NEAREST: {
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result = nearest(x)->second;
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break;
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}
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case InterpType::QUADRATIC: {
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double xs[3], ys[3], as[3];
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auto it = nearest(x);
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if (it == value_.begin()) {
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it = next(it);
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}
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else if (it == prev(value_.end())) {
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it = prev(it);
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}
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xs[0] = prev(it)->first;
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ys[0] = prev(it)->second;
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xs[1] = it->first;
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ys[1] = it->second;
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xs[2] = next(it)->first;
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ys[2] = next(it)->second;
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// Lagrange polynomial coefficient computation
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as[0]
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= (x - xs[1]) / (xs[0] - xs[1])
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* (x - xs[2]) / (xs[0] - xs[2]);
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as[1]
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= (x - xs[0]) / (xs[1] - xs[0])
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* (x - xs[2]) / (xs[1] - xs[2]);
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as[2]
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= (x - xs[0]) / (xs[2] - xs[0])
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* (x - xs[1]) / (xs[2] - xs[1]);
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result = as[0] * ys[0] + as[1] * ys[1] + as[2] * ys[2];
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break;
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}
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default:
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int intType = static_cast<int>(interpType_);
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LATAN_ERROR(Implementation, "unsupported interpolation type in "
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"tabulated function: "
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+ strFrom(intType));
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}
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auto i = value_.equal_range(x);
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auto low = (x == i.first->first) ? i.first : prev(i.first);
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auto high = i.second;
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x_a = low->first;
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x_b = high->first;
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y_a = low->second;
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y_b = high->second;
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return y_a + (x - x_a)*(y_b - y_a)/(x_b - x_a);
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return result;
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}
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// DoubleFunction factory //////////////////////////////////////////////////////
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@ -101,13 +149,30 @@ DoubleFunction TabFunction::makeFunction(const bool makeHardCopy) const
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return res;
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}
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DoubleFunction Latan::interpolate(const DVec &x, const DVec &y)
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DoubleFunction Latan::interpolate(const DVec &x, const DVec &y,
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const InterpType interpType)
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{
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return TabFunction(x,y).makeFunction();
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return TabFunction(x, y, interpType).makeFunction();
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}
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DoubleFunction Latan::interpolate(const XYStatData &data, const Index i,
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const Index j)
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const Index j, const InterpType interpType)
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{
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return TabFunction(data, i, j).makeFunction();
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return TabFunction(data, i, j, interpType).makeFunction();
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}
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map<double, double>::const_iterator TabFunction::nearest(const double x) const
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{
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map<double, double>::const_iterator ret;
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auto i = value_.equal_range(x);
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auto low = (x == i.first->first) ? i.first : prev(i.first);
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auto high = i.second;
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if (fabs(high->first - x) < fabs(low->first - x)) {
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ret = high;
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}
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else {
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ret = low;
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}
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return ret;
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}
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@ -20,9 +20,11 @@
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#ifndef Latan_TabFunction_hpp_
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#define Latan_TabFunction_hpp_
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#include <algorithm>
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#include <map>
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#include <LatAnalyze/Global.hpp>
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#include <LatAnalyze/Function.hpp>
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#include <LatAnalyze/Math.hpp>
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#include <LatAnalyze/XYStatData.hpp>
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BEGIN_LATAN_NAMESPACE
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@ -31,13 +33,22 @@ BEGIN_LATAN_NAMESPACE
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* tabulated function: 1D only *
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******************************************************************************/
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enum class InterpType
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{
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NEAREST,
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LINEAR,
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QUADRATIC
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};
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class TabFunction: public DoubleFunctionFactory
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{
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public:
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// constructors
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TabFunction(void) = default;
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TabFunction(const DVec &x, const DVec &y);
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TabFunction(const XYStatData &data, const Index i = 0, const Index j = 0);
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TabFunction(const DVec &x, const DVec &y,
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const InterpType interpType = InterpType::LINEAR);
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TabFunction(const XYStatData &data, const Index i = 0, const Index j = 0,
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const InterpType interpType = InterpType::LINEAR);
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// destructor
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virtual ~TabFunction(void) = default;
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// access
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@ -48,12 +59,17 @@ public:
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// factory
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virtual DoubleFunction makeFunction(const bool makeHardCopy = true) const;
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private:
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std::map<double, double>::const_iterator nearest(const double x) const;
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std::map<double, double> value_;
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InterpType interpType_;
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};
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DoubleFunction interpolate(const DVec &x, const DVec &y);
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DoubleFunction interpolate(const DVec &x, const DVec &y,
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const InterpType interpType = InterpType::LINEAR);
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DoubleFunction interpolate(const XYStatData &data, const Index i = 0,
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const Index j = 0);
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const Index j = 0,
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const InterpType interpType = InterpType::LINEAR);
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END_LATAN_NAMESPACE
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