/*    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 CONCEPT_COXETER_TRIANGULATION_FUNCTION_FOR_IMPLICIT_MANIFOLD_H_
#define CONCEPT_COXETER_TRIANGULATION_FUNCTION_FOR_IMPLICIT_MANIFOLD_H_

#include <cstdlib>  // for std::size_t

#include <Eigen/Dense>

namespace Gudhi {

namespace coxeter_triangulation {

/** \brief The concept FunctionForImplicitManifold describes the requirements
 * for a type to implement an implicit function class used for example in Manifold_tracing.
 */
struct FunctionForImplicitManifold {
  /** \brief Value of the function at a specified point 'p'.
   *  @param[in] p The input point given by its Cartesian coordinates.
   *  Its size needs to be equal to amb_d().
   */
  Eigen::VectorXd operator()(const Eigen::VectorXd& p) const;

  /** \brief Returns the domain (ambient) dimension. */
  std::size_t amb_d() const;

  /** \brief Returns the codomain dimension. */
  std::size_t cod_d() const;

  /** \brief Returns a point on the zero-set of the function. */
  Eigen::VectorXd seed() const;
};

}  // namespace coxeter_triangulation

}  // namespace Gudhi

#endif