griewank.cpp

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

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

namespace pagmo { namespace problem {


griewank::griewank(int n):base(n)
{
        // Set bounds.
        set_lb(-600);
        set_ub(600);
}

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

void griewank::objfun_impl(fitness_vector &f, const decision_vector &x) const
{
        pagmo_assert(f.size() == 1);
        decision_vector::size_type n = x.size();
        double fr=4000.0;
        double retval = 0.0;
        double p = 1.0;

        for (decision_vector::size_type i=0; i<n; i++){ retval += x[i]*x[i];}
        for (decision_vector::size_type i=0; i<n; i++){ p *= cos(x[i]/sqrt(i+1.0));}
        f[0] = (retval/fr - p + 1);
}

std::string griewank::get_name() const
{
        return "Griewank";
}

}} //namespaces

BOOST_CLASS_EXPORT_IMPLEMENT(pagmo::problem::griewank)