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/*************************************************************************
* Copyright (C) 2010 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The vZ Test Suite. *
* *
* The vZ Test Suite 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. *
* *
* The vZ Test Suite 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 this program. If not, see <http://www.gnu.org/licenses/>. *
*************************************************************************/
#include "vZ.hpp"
#include <cmath>
#include <cstdlib>
#include <iostream>
#include <iomanip>
typedef vZ::EquationSystem<2> Y;
// y'' = y (y == C*exp(t))
Y
f(double t, Y y)
{
Y r;
r[0] = y[1];
r[1] = y[0];
return r;
}
int
main()
{
Y y;
y[0] = 1.0;
y[1] = 1.0;
vZ::GenericDP45Integrator<Y> integrator(f);
integrator.tol(1e-6)
.y(y)
.x(0.0)
.h(0.06);
integrator.integrate(2.0);
double actual = integrator.y()[0];
double expected = std::exp(2.0);
std::cout << std::setprecision(10)
<< "Numerical: " << actual << std::endl
<< "Expected: " << expected << std::endl
<< "h: " << integrator.h() << std::endl
<< "Iterations: " << integrator.iterations() << std::endl
<< "Rejections: " << integrator.rejections() << std::endl;
double error = std::fabs(expected - actual)/expected;
if (error > 6.0e-7) {
std::cerr << "Error: " << 100.0*error << "%" << std::endl;
return EXIT_FAILURE;
} else {
std::cout << "Error: " << 100.0*error << "%" << std::endl;
return EXIT_SUCCESS;
}
}
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