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/*!
* \file
* \brief Transforms test program
* \author Tony Ottosson, Thomas Eriksson, Simon Wood, Adam Piatyszek, Andy Panov and Bogdan Cristea
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2013 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* IT++ 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along
* with IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include <itpp/itbase.h>
#include "gtest/gtest.h"
using namespace std;
using namespace itpp;
//Integration is tested with x*ln(x) function
double test_integrand(const double x)
{
return x * log(x);
}
struct Test_Integrand {
double operator()(double x) {
return x * log(x);
}
};
//set test tolerance (measure of relative and absolute error)
const double max_rel_error = 1e-6;
const double max_abs_error = 1e-6;
//results tester
inline void test_result(double q, double ref)
{
if(abs(q - ref) < max_abs_error) return; //handle numbers with absolute value close to zero (relative error can be huge for them)
double rel_error = abs(q - ref) / abs(q);
ASSERT_LE(rel_error, max_rel_error);
}
//analytically computed integral
double integral_value(double a, double b)
{
return 0.25 * b * b * (2 * log(b) - 1.0) - 0.25 * a * a * (2 * log(a) - 1.0);
}
//----------------------------------------------
//Gtest test cases
//----------------------------------------------
static const double low_lim = 1.5;
static const double hi_lim = 3.5;
static const double ref_integral_value = integral_value(low_lim, hi_lim);
TEST(Integration, Simpson)
{
{
SCOPED_TRACE("Testing function object");
double q = itpp::quad(Test_Integrand(), low_lim, hi_lim);
test_result(q, ref_integral_value);
}
{
SCOPED_TRACE("Testing double f(double)");
double q = itpp::quad(test_integrand, low_lim, hi_lim);
test_result(q, ref_integral_value);
}
}
TEST(Integration, Lobatto)
{
{
SCOPED_TRACE("Testing function object");
double q = itpp::quadl(Test_Integrand(), low_lim, hi_lim);
test_result(q, ref_integral_value);
}
{
SCOPED_TRACE("Testing double f(double)");
double q = itpp::quadl(test_integrand, low_lim, hi_lim);
test_result(q, ref_integral_value);
}
}
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