ackley.cpp

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#include <boost/math/constants/constants.hpp>
#include <cmath>
#include <string>


#include "../exceptions.h"
#include "../types.h"
#include "base.h"
#include "ackley.h"

namespace pagmo { namespace problem {


ackley::ackley(int n):base(n)
{
        // Set bounds.
        set_lb(-15.0);
        set_ub(30);

        // Initialise global minima vector vector vector vector
        std::vector<decision_vector> best_x(1);
        // The Ackley problem has only one global minimum: at (0, ..., 0)
        // (the value for all dimensions is 0).
        for(int i = 0; i < n; ++i) {
                best_x[0].push_back(0);
        }

        set_best_x(best_x);
}

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

void ackley::objfun_impl(fitness_vector &f, const decision_vector &x) const
{
        pagmo_assert(f.size() == 1);
        std::vector<double>::size_type n = x.size();
        f[0]=0;

        double omega = 2.0 * M_PI;
        double s1=0.0, s2=0.0;
        double nepero=exp(1.0);

        for (std::vector<double>::size_type i=0; i<n; i++){
                s1 += x[i]*x[i];
                s2 += cos(omega*x[i]);
        }
        f[0] = -20*exp(-0.2 * sqrt(1.0/n * s1))-exp(1.0/n*s2)+ 20 + nepero;
}

std::string ackley::get_name() const
{
        return "Ackley";
}

}}

BOOST_CLASS_EXPORT_IMPLEMENT(pagmo::problem::ackley)