SphereFunction.h

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#ifndef SPHERE_FUNCTION_H
#define SPHERE_FUNCTION_H
 
#pragma once
 
/*
 * @file SphereFunction.h
 * - Global Minimum: It has a single global minimum at the origin
 * x = (0, 0, ..., 0), where f(x) = 0.
 * - Local Minimum: There are NO local minimum other than the global one.
 * - Shape: Geometrically, it represents an n-dimensional paraboloid.
 */
 
#include "core/FitnessFunction.h"
#include <vector>
 
namespace galib::benchmark {
 
    template <typename GeneType = double>
        class SphereFunction : public FitnessFunction<GeneType> {
        private:
            std::size_t dimensions;
            GeneType lower_bound;
            GeneType upper_bound;
        public:
            explicit SphereFunction(const std::size_t dim, GeneType lb, GeneType ub)
                : dimensions(dim), lower_bound(lb), upper_bound(ub) {}
 
            double evaluate(const std::vector<GeneType>& phenotype) const override {
                double sum = 0;
                for (GeneType gene : phenotype) {
                    sum += static_cast<double>(gene * gene);
                }
                return sum;
            }
 
            std::size_t size()  const override { return dimensions; }
            std::string name()  const override { return "Sphere"; }
 
            GeneType getLowerBound(std::size_t) const override { return lower_bound; }
            GeneType getUpperBound(std::size_t) const override { return upper_bound; }
        };
 
}
 
#endif // SPHERE_FUNCTION_H