Linear_transformation.h

/*    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_LINEAR_TRANSFORMATION_H_
#define FUNCTIONS_LINEAR_TRANSFORMATION_H_
 
#include <cstdlib>  // for std::size_t
 
#include <Eigen/Dense>
 
namespace Gudhi {
 
namespace coxeter_triangulation {
 
template <class Function_>
struct Linear_transformation {
  Eigen::VectorXd operator()(const Eigen::VectorXd& p) const {
    Eigen::VectorXd result = fun_(matrix_.householderQr().solve(p));
    return result;
  }
 
  std::size_t amb_d() const { return fun_.amb_d(); }
 
  std::size_t cod_d() const { return fun_.cod_d(); }
 
  Eigen::VectorXd seed() const {
    Eigen::VectorXd result = fun_.seed();
    result = matrix_ * result;
    return result;
  }
 
  Linear_transformation(const Function_& function, const Eigen::MatrixXd& matrix) : fun_(function), matrix_(matrix) {}
 
 private:
  Function_ fun_;
  Eigen::MatrixXd matrix_;
};
 
template <class Function_>
Linear_transformation<Function_> make_linear_transformation(const Function_& function, const Eigen::MatrixXd& matrix) {
  return Linear_transformation<Function_>(function, matrix);
}
 
}  // namespace coxeter_triangulation
 
}  // namespace Gudhi
 
#endif