lavor_maculan.cpp

/*****************************************************************************
 *   Copyright (C) 2004-2015 The PaGMO development team,                     *
 *   Advanced Concepts Team (ACT), European Space Agency (ESA)               *
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 *   https://github.com/esa/pagmo                                            *
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 *   act@esa.int                                                             *
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#include <string>

#include "../exceptions.h"
#include "../types.h"
#include "base.h"
#include <cmath>
#include "lavor_maculan.h"

namespace pagmo { namespace problem {


lavor_maculan::lavor_maculan(int atoms): base(atoms - 3)
{
        if (atoms <= 0 || atoms < 4) {
                pagmo_throw(value_error, "number of atoms for lavor-maculan problem must be positive and greater than 3");
        }
        // Set bounds.
        set_lb(0.0);
        set_ub(5.0);

        // Initialise global minima vector
        std::vector<decision_vector> best_x(1);
        // Single global minimum of Lavor Maculan is a repeating sequence of
        // (1.039195303, 3.141592654, 1.039195303, 3.141592654, 1.039195303, ...)
        double rep[] = {1.039195303, 3.141592654};
        for(int i = 0; i < atoms - 3; ++i) {
                best_x[0].push_back(rep[i % 2]);
        }

        set_best_x(best_x);
}

base_ptr lavor_maculan::clone() const
{
        return base_ptr(new lavor_maculan(*this));
}

void lavor_maculan::objfun_impl(fitness_vector &f, const decision_vector &x) const
{
        const decision_vector::size_type n = x.size();
        f[0] = 0.0;
        for (decision_vector::size_type i = 0 ; i < n ; ++i) {
                f[0] += 1 + cos(3 * x[i]) + (((i % 2 == 1) ? 1 : -1) / (sqrt(10.60099896 - 4.141720682 * cos(x[i]))));
        }
}

std::string lavor_maculan::get_name() const
{
        return "Lavor Maculan";
}

}}

BOOST_CLASS_EXPORT_IMPLEMENT(pagmo::problem::lavor_maculan)