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/* This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
* See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
* Author(s): Siargey Kachanovich
*
* Copyright (C) 2019 Inria
*
* Modification(s):
* - YYYY/MM Author: Description of the modification
*/
#ifndef FUNCTIONS_CONSTANT_FUNCTION_H_
#define FUNCTIONS_CONSTANT_FUNCTION_H_
#include <cstdlib> // for std::size_t
#include <gudhi/Functions/Function.h>
#include <Eigen/Dense>
namespace Gudhi {
namespace coxeter_triangulation {
/**
* \class Constant_function
* \brief A class that encodes a constant function from R^d to R^k.
* This class does not have any implicit manifold in correspondence.
*/
struct Constant_function : public Function {
/** \brief Value of the function at a specified point. The value is constant.
* @param[in] p The input point. The dimension needs to coincide with the ambient dimension.
*/
virtual Eigen::VectorXd operator()(const Eigen::VectorXd& p) const override {
Eigen::VectorXd result = value_;
return result;
}
/** \brief Returns the domain dimension. Same as the ambient dimension of the sphere. */
virtual std::size_t amb_d() const override { return d_; };
/** \brief Returns the codomain dimension. Same as the codimension of the sphere. */
virtual std::size_t cod_d() const override { return k_; };
/** \brief No seed point is available. Throws an exception on evocation. */
virtual Eigen::VectorXd seed() const override { throw "Seed invoked on a constant function.\n"; }
Constant_function() {}
/**
* \brief Constructor of a constant function from R^d to R^m.
*
* @param[in] d The domain dimension.
* @param[in] k The codomain dimension.
* @param[in] value The constant value of the function.
*/
Constant_function(std::size_t d, std::size_t k, const Eigen::VectorXd& value) : d_(d), k_(k), value_(value) {}
private:
std::size_t d_, k_;
Eigen::VectorXd value_;
};
} // namespace coxeter_triangulation
} // namespace Gudhi
#endif
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