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/*************************************************************************
* Copyright (C) 2009-2010 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The vZ Library. *
* *
* The vZ Library 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. *
* *
* The vZ Library 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 this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
#ifndef VZ_INTEGRATOR_HPP
#define VZ_INTEGRATOR_HPP
#include <tr1/functional>
#include <algorithm>
namespace vZ
{
// Base Integrator class
//
// All integration methods derive from this class
// If the initial value problem is specified as
// y' = f(x, y); y(x0) = y0
// then an Integrator could be constructed as Integrator(f, dt).y(y0).x(x0)
template <typename Y>
class GenericIntegrator
{
public:
typedef typename Traits<Y>::Scalar Scalar;
typedef std::tr1::function<Y (Scalar, Y)> Function;
// By default, y and t start at zero, h starts UNDEFINED
GenericIntegrator(Function f)
: m_f(f), m_y(0), m_x(0), m_h() { }
virtual ~GenericIntegrator() { }
GenericIntegrator& y(Y y) { m_y = y; return *this; }
GenericIntegrator& x(Scalar x) { m_x = x; return *this; }
GenericIntegrator& h(Scalar h) { m_h = h; return *this; }
Y y() const { return m_y; }
Scalar x() const { return m_x; }
Scalar h() const { return m_h; }
// Integrate until x == x_final
void integrate(Scalar x_final);
protected:
virtual void step() = 0;
const Function& f() const { return m_f; }
private:
Function m_f;
Y m_y;
Scalar m_x, m_h;
};
// Type alias
typedef GenericIntegrator<double> Integrator;
// Implementations
template <typename Y>
void
GenericIntegrator<Y>::integrate(Scalar x_final)
{
while (m_x < x_final) {
m_h = std::min(m_h, x_final - m_x);
step();
}
}
}
#endif // VZ_INTEGRATOR_HPP
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