pressure_vessel.cpp

/*****************************************************************************
 *   Copyright (C) 2004-2015 The PaGMO development team,                     *
 *   Advanced Concepts Team (ACT), European Space Agency (ESA)               *
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#include <boost/math/constants/constants.hpp>

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

static const std::vector<double> __constraint_tolerances__(int c_dimension, int ic_dimension)
{
        std::vector<double> constraint_tolerances(c_dimension);
        // equality constraints
        for(int i=0; i<c_dimension-ic_dimension; i++) {
                constraint_tolerances[i] = 0.0001;
        }
        // inequality constraints
        for(int i=c_dimension-ic_dimension; i<c_dimension; i++) {
                constraint_tolerances[i] = 0.;
        }
        return constraint_tolerances;
}

namespace pagmo { namespace problem {


pressure_vessel::pressure_vessel():base(4,0,1,4,4,__constraint_tolerances__(4,4))
{
        // initialize best solution
        initialize_best();

        // set the bounds for the current problem
        const double lb[] = {1.,1.,10.,10.};
        const double ub[] = {99.,99.,200.,200.};
        set_bounds(lb,ub);
}

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

void pressure_vessel::objfun_impl(fitness_vector &f, const decision_vector &x) const
{
        /* objective function */
        f[0] = 0.6224 * x[0] * x[2] * x[3] +
                        1.7781 * x[1] * x[2]*x[2] +
                        3.1661 * x[0]*x[0] * x[3] +
                        19.84 * x[0]*x[0] * x[2];
}

void pressure_vessel::compute_constraints_impl(constraint_vector &c, const decision_vector &x) const
{
        /* constraints g<=0 */
        c[0] = - x[0] + 0.0193 * x[2];
        c[1] = - x[1] + 0.00954 * x[2];
        c[2] = - boost::math::constants::pi<double>() * x[2]*x[2] * x[3] -
                        (4./3.) * boost::math::constants::pi<double>() * x[2]*x[2]*x[2] + 1296000.;
        c[3] = x[3] - 240.;
}

std::string pressure_vessel::get_name() const
{
        std::string retval("Pressure vessel");
        return retval;
}

void pressure_vessel::initialize_best(void)
{
        std::vector<decision_vector> best_x;

        int x_dimension = 4;
        // Coello and Montes
        const double x_vector[] = {0.812500, 0.437500, 42.097398, 176.654050};

        decision_vector x(x_dimension);
        std::copy(x_vector,x_vector + x_dimension,x.begin());
        best_x.push_back(x);

        set_best_x(best_x);
}

}} //namespaces

BOOST_CLASS_EXPORT_IMPLEMENT(pagmo::problem::pressure_vessel)