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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_NEGATION_H_
#define FUNCTIONS_NEGATION_H_
#include <cstdlib>
#include <gudhi/Functions/Function.h>
#include <Eigen/Dense>
namespace Gudhi {
namespace coxeter_triangulation {
/**
*\class Negation
* \brief Constructs the "minus" function. The zero-set is the same, but
* the values at other points are the negative of their original value.
*
* \tparam Function_ The function template parameter. Should be a model of
* the concept FunctionForImplicitManifold.
*
* \ingroup coxeter_triangulation
*/
template <class Function_>
struct Negation : 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.
*/
virtual Eigen::VectorXd operator()(const Eigen::VectorXd& p) const override {
Eigen::VectorXd result = -fun_(p);
return result;
}
/** \brief Returns the domain (ambient) dimension. */
virtual std::size_t amb_d() const override {return fun_.amb_d();}
/** \brief Returns the codomain dimension. */
virtual std::size_t cod_d() const override {return fun_.cod_d();}
/** \brief Returns a point on the zero-set. */
virtual Eigen::VectorXd seed() const override {
Eigen::VectorXd result = fun_.seed();
return result;
}
/**
* \brief Constructor of the negative function.
*
* @param[in] function The function to be negated.
*/
Negation(const Function_& function) :
fun_(function) {
}
Function_ fun_;
};
/**
* \brief Static constructor of the negative function.
*
* @param[in] function The function to be translated.
* domain (ambient) dimension of 'function'.
*
* \tparam Function_ The function template parameter. Should be a model of
* the concept FunctionForImplicitManifold.
*
* \ingroup coxeter_triangulation
*/
template <class Function_>
Negation<Function_> negation(const Function_& function) {
return Negation<Function_>(function);
}
} // namespace coxeter_triangulation
} // namespace Gudhi
#endif
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