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Diffstat (limited to 'src/Coxeter_triangulation/include/gudhi/Functions/Cartesian_product.h')
| -rw-r--r-- | src/Coxeter_triangulation/include/gudhi/Functions/Cartesian_product.h | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/src/Coxeter_triangulation/include/gudhi/Functions/Cartesian_product.h b/src/Coxeter_triangulation/include/gudhi/Functions/Cartesian_product.h new file mode 100644 index 00000000..0533bb83 --- /dev/null +++ b/src/Coxeter_triangulation/include/gudhi/Functions/Cartesian_product.h @@ -0,0 +1,157 @@ +/* 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_CARTESIAN_PRODUCT_H_ +#define FUNCTIONS_CARTESIAN_PRODUCT_H_ + +#include <cstdlib> +#include <tuple> +#include <type_traits> // for std::enable_if +#include <cstdlib> // for std::size_t + +#include <Eigen/Dense> + +namespace Gudhi { + +namespace coxeter_triangulation { + +/* Get the domain dimension of the tuple of functions. + */ +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I == sizeof...(T), std::size_t>::type get_amb_d(const std::tuple<T...>& tuple) { + return 0; +} + +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I != sizeof...(T), std::size_t>::type get_amb_d(const std::tuple<T...>& tuple) { + return std::get<I>(tuple).amb_d() + get_amb_d<I + 1, T...>(tuple); +} + +/* Get the codomain dimension of the tuple of functions. + */ +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I == sizeof...(T), std::size_t>::type get_cod_d(const std::tuple<T...>& tuple) { + return 0; +} + +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I != sizeof...(T), std::size_t>::type get_cod_d(const std::tuple<T...>& tuple) { + return std::get<I>(tuple).cod_d() + get_cod_d<I + 1, T...>(tuple); +} + +/* Get the seed of the tuple of functions. + */ +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I == sizeof...(T), void>::type get_seed(const std::tuple<T...>& tuple, + Eigen::VectorXd& point, std::size_t i = 0) {} + +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I != sizeof...(T), void>::type get_seed(const std::tuple<T...>& tuple, + Eigen::VectorXd& point, std::size_t i = 0) { + const auto& f = std::get<I>(tuple); + std::size_t n = f.amb_d(); + Eigen::VectorXd seed = f.seed(); + for (std::size_t j = 0; j < n; ++j) point(i + j) = seed(j); + get_seed<I + 1, T...>(tuple, point, i + n); +} + +/* Get the seed of the tuple of functions. + */ +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I == sizeof...(T), void>::type get_value(const std::tuple<T...>& tuple, + const Eigen::VectorXd& x, + Eigen::VectorXd& point, std::size_t i = 0, + std::size_t j = 0) {} + +template <std::size_t I = 0, typename... T> +inline typename std::enable_if<I != sizeof...(T), void>::type get_value(const std::tuple<T...>& tuple, + const Eigen::VectorXd& x, + Eigen::VectorXd& point, std::size_t i = 0, + std::size_t j = 0) { + const auto& f = std::get<I>(tuple); + std::size_t n = f.amb_d(); + std::size_t k = f.cod_d(); + Eigen::VectorXd x_i(n); + for (std::size_t l = 0; l < n; ++l) x_i(l) = x(i + l); + Eigen::VectorXd res = f(x_i); + for (std::size_t l = 0; l < k; ++l) point(j + l) = res(l); + get_value<I + 1, T...>(tuple, x, point, i + n, j + k); +} + +/** + * \class Cartesian_product + * \brief Constructs the function the zero-set of which is the Cartesian product + * of the zero-sets of some given functions. + * + * \tparam Functions A pack template parameter for functions. All functions should be models of + * the concept FunctionForImplicitManifold. + */ +template <class... Functions> +struct Cartesian_product { + /** + * \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(cod_d_); + get_value(function_tuple_, p, result, 0, 0); + return result; + } + + /** \brief Returns the domain (ambient) dimension. */ + std::size_t amb_d() const { return amb_d_; } + + /** \brief Returns the codomain dimension. */ + std::size_t cod_d() const { return cod_d_; } + + /** \brief Returns a point on the zero-set. */ + Eigen::VectorXd seed() const { + Eigen::VectorXd result(amb_d_); + get_seed(function_tuple_, result, 0); + return result; + } + + /** + * \brief Constructor of the Cartesian product function. + * + * @param[in] functions The functions the zero-sets of which are factors in the + * Cartesian product of the resulting function. + */ + Cartesian_product(const Functions&... functions) : function_tuple_(std::make_tuple(functions...)) { + amb_d_ = get_amb_d(function_tuple_); + cod_d_ = get_cod_d(function_tuple_); + } + + private: + std::tuple<Functions...> function_tuple_; + std::size_t amb_d_, cod_d_; +}; + +/** + * \brief Static constructor of a Cartesian product function. + * + * @param[in] functions The functions the zero-sets of which are factors in the + * Cartesian product of the resulting function. + * + * \tparam Functions A pack template parameter for functions. All functions should be models of + * the concept FunctionForImplicitManifold. + * + * \ingroup coxeter_triangulation + */ +template <typename... Functions> +Cartesian_product<Functions...> make_product_function(const Functions&... functions) { + return Cartesian_product<Functions...>(functions...); +} + +} // namespace coxeter_triangulation + +} // namespace Gudhi + +#endif |