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#include <cmath>
#include <initializer_list>
#include <iostream>
#include <utility>
#include <pagmo/problem.hpp>
#include <pagmo/types.hpp>
using namespace pagmo;
// Our simple example problem, version 1.
struct problem_v1 {
// Number of equality constraints.
vector_double::size_type get_nec() const
{
return 1;
}
// Number of inequality constraints.
vector_double::size_type get_nic() const
{
return 1;
}
// Implementation of the objective function.
vector_double fitness(const vector_double &dv) const
{
return {
dv[0] * dv[3] * (dv[0] + dv[1] + dv[2]) + dv[2], // objfun
dv[0] * dv[0] + dv[1] * dv[1] + dv[2] * dv[2] + dv[3] * dv[3] - 40., // equality con.
25. - dv[0] * dv[1] * dv[2] * dv[3] // inequality con.
};
}
// Implementation of the box bounds.
std::pair<vector_double, vector_double> get_bounds() const
{
return {{1., 1., 1., 1.}, {5., 5., 5., 5.}};
}
};
int main()
{
// Construct a pagmo::problem from our example problem.
problem p{problem_v1{}};
// Compute the value of the objective function, equality and
// inequality constraints in the point (1, 2, 3, 4).
const auto fv = p.fitness({1, 2, 3, 4});
std::cout << "Value of the objfun in (1, 2, 3, 4): " << fv[0] << '\n';
std::cout << "Value of the eq. constraint in (1, 2, 3, 4): " << fv[1] << '\n';
std::cout << "Value of the ineq. constraint in (1, 2, 3, 4): " << fv[2] << '\n';
// Fetch the lower/upper bounds for the first variable.
std::cout << "Lower bounds: [" << p.get_lb()[0] << "]\n";
std::cout << "Upper bounds: [" << p.get_ub()[0] << "]\n\n";
// Print p to screen.
std::cout << p << '\n';
}
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