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+/*    This file is part of the Gudhi Library. The Gudhi library
+ *    (Geometric Understanding in Higher Dimensions) is a generic C++
+ *    library for computational topology.
+ *
+ *    Author(s):       Siargey Kachanovich
+ *
+ *    Copyright (C) 2019 Inria
+ *
+ *    Modification(s):
+ *      - YYYY/MM Author: Description of the modification
+ */
+
+#ifndef FUNCTIONS_EMBED_IN_RD_H_
+#define FUNCTIONS_EMBED_IN_RD_H_
+
+#include <cstdlib>
+#include <random>
+
+#include <gudhi/Functions/Function.h>
+#include <Eigen/Dense>
+
+
+namespace Gudhi {
+
+namespace coxeter_triangulation {
+
+/**
+ * \class Embed_in_Rd
+ * \brief Embedding of an implicit manifold in a higher dimension.
+ *
+ * \tparam Function_ The function template parameter. Should be a model of 
+ * the concept FunctionForImplicitManifold.
+ *
+ * \ingroup coxeter_triangulation
+ */
+template <class Function_>
+struct Embed_in_Rd : public Function {
+  
+  /** 
+   * \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 x = p;
+    Eigen::VectorXd x_k(fun_.amb_d()), x_rest(d_ - fun_.amb_d());
+    for (std::size_t i = 0; i < fun_.amb_d(); ++i)
+      x_k(i) = x(i);
+    for (std::size_t i = fun_.amb_d(); i < d_; ++i)
+      x_rest(i - fun_.amb_d()) = x(i);
+    Eigen::VectorXd result = fun_(x_k);
+    result.conservativeResize(this->cod_d());
+    for (std::size_t i = fun_.cod_d(); i < this->cod_d(); ++i)
+      result(i) = x_rest(i - fun_.cod_d());
+    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 d_-(fun_.amb_d() - fun_.cod_d());}
+
+  /** \brief Returns a point on the zero-set of the embedded function. */
+  Eigen::VectorXd seed() const {
+    Eigen::VectorXd result = fun_.seed();
+    result.conservativeResize(d_);
+    for (std::size_t l = fun_.amb_d(); l < d_; ++l)
+      result(l) = 0;
+    return result;
+  }
+
+  /** 
+   * \brief Constructor of the embedding function.
+   *
+   * @param[in] function The function to be embedded in higher dimension.
+   * @param[in] d Embedding dimension.
+   */
+  Embed_in_Rd(const Function_& function, std::size_t d) :
+    fun_(function), d_(d) {
+  }
+  Function_ fun_;
+  std::size_t d_;
+};
+
+
+/** 
+ * \brief Static constructor of an embedding function.
+ *
+ * @param[in] function The function to be embedded in higher dimension.
+ * @param[in] d Embedding dimension.
+ *
+ * \tparam Function_ The function template parameter. Should be a model of 
+ * the concept FunctionForImplicitManifold.
+ *
+ * \ingroup coxeter_triangulation
+ */
+template <class Function_>
+Embed_in_Rd<Function_> make_embedding(const Function_& function, std::size_t d) {
+  return Embed_in_Rd<Function_>(function, d);
+}
+
+} // namespace coxeter_triangulation
+
+} // namespace Gudhi
+
+#endif