test_functions.h

// Pallas Solver
// Copyright 2015. All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
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// * Redistributions in binary form must reproduce the above copyright notice,
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// Author: ryan.latture@gmail.com (Ryan Latture)

#ifndef PALLAS_TEST_FUNCTIONS_H
#define PALLAS_TEST_FUNCTIONS_H

#include "pallas/types.h"

#include <cmath>

#define PI           3.14159265358979323846

namespace pallas {
    namespace internal {
        using std::cos;
        using std::sin;
        using std::sqrt;
        using std::exp;
        using std::abs;

        static const double pow_LUT[2] = { 1.0, -1.0 };

        double schwefel(const Vector &x)
        {
            unsigned int num = x.size();
            double s = 0.0;
            for (unsigned int i = 0; i < num; ++i)
            {
                s += -x(i) * sin(sqrt(abs(x(i))));
            }
            return 418.9829 * num + s;
        }

        double rosenbrock(const Vector &x)
        {
            unsigned int num = x.size();
            double s = 0.0;
            for (unsigned int i = 0; i < (num - 1); ++i)
            {
                s += (x(i+1) - x(i)*x(i))*(x(i+1) - x(i)*x(i)) + (1-x(i)) * (1-x(i));
            }
            return 100.0 * s;
        }

        double easom(const Vector &x)
        {
            unsigned int num = x.size();
            double sm = 0.0;
            double tm = 1.0;
            for (unsigned int i = 0; i < num; ++i)
            {
                sm += (x(i) - PI)*(x(i) - PI);
                tm *= cos(x(i))*cos(x(i));
            }
            return -(pow_LUT[num % 2]) * tm * exp(-sm) + 1.0;
        }

        double xsy02(const Vector &x)
        {
            unsigned int num = x.size();
            double sm1 = 0.0;
            double sm2 = 0.0;
            for (unsigned int i = 0; i < num; ++i)
            {
                sm1 += abs(x(i));
                sm2 += sin(x(i)*x(i));
            }
            return sm1 / exp(sm2);
        }
    }
}

#endif // PALLAS_TEST_FUNCTIONS_H