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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_FUNCTION_MOMENT_CURVE_IN_RD_H_
#define FUNCTIONS_FUNCTION_MOMENT_CURVE_IN_RD_H_
#include <cstdlib> // for std::size_t
#include <Eigen/Dense>
namespace Gudhi {
namespace coxeter_triangulation {
/**
* \class Function_moment_curve_in_Rd
* \brief A class for the function that defines an implicit moment curve
* in the d-dimensional Euclidean space.
*/
struct Function_moment_curve_in_Rd {
/** \brief Value of the function at a specified point.
* @param[in] p The input point. The dimension needs to coincide with the ambient dimension.
*/
Eigen::VectorXd operator()(const Eigen::VectorXd& p) const {
Eigen::VectorXd result(k_);
for (std::size_t i = 1; i < d_; ++i) result(i - 1) = p(i) - p(0) * p(i - 1);
return result;
}
/** \brief Returns the domain (ambient) dimension.. */
std::size_t amb_d() const { return d_; };
/** \brief Returns the codomain dimension. */
std::size_t cod_d() const { return k_; };
/** \brief Returns a point on the moment curve. */
Eigen::VectorXd seed() const {
Eigen::VectorXd result = Eigen::VectorXd::Zero(d_);
return result;
}
/**
* \brief Constructor of the function that defines an implicit moment curve
* in the d-dimensional Euclidean space.
*
* @param[in] r Numerical parameter.
* @param[in] d The ambient dimension.
*/
Function_moment_curve_in_Rd(double r, std::size_t d) : m_(1), k_(d - 1), d_(d), r_(r) {}
/**
* \brief Constructor of the function that defines an implicit moment curve
* in the d-dimensional Euclidean space.
*
* @param[in] r Numerical parameter.
* @param[in] d The ambient dimension.
* @param[in] offset The offset of the moment curve.
*/
Function_moment_curve_in_Rd(double r, std::size_t d, Eigen::VectorXd& offset)
: m_(1), k_(d - 1), d_(d), r_(r), off_(offset) {}
private:
std::size_t m_, k_, d_;
double r_;
Eigen::VectorXd off_;
};
} // namespace coxeter_triangulation
} // namespace Gudhi
#endif
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