107 lines
3.8 KiB
C++
107 lines
3.8 KiB
C++
/* ***********************************************************************
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//
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// Copyright (C) 2025 -- The 4D-STAR Collaboration
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// File Author: Emily Boudreaux
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// Last Modified: April 21, 2025
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//
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// 4DSSE is free software; you can use it and/or modify
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// it under the terms and restrictions the GNU General Library Public
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// License version 3 (GPLv3) as published by the Free Software Foundation.
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//
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// 4DSSE is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public License
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// along with this software; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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// *********************************************************************** */
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#pragma once
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#include "mfem.hpp"
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#include <string>
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#include "config.h"
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#include "probe.h"
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/**
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* @file integrators.h
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* @brief A collection of utilities for working with MFEM and solving the lane-emden equation.
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*/
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namespace serif {
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namespace polytrope {
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/**
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* @namespace polyMFEMUtils
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* @brief A namespace for utilities for working with MFEM and solving the lane-emden equation.
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*/
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namespace polyMFEMUtils {
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/**
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* @brief A class for nonlinear power integrator.
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*/
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class NonlinearPowerIntegrator: public mfem::NonlinearFormIntegrator {
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public:
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/**
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* @brief Constructor for NonlinearPowerIntegrator.
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*
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* @param coeff The function coefficient.
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* @param n The polytropic index.
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*/
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NonlinearPowerIntegrator(double n);
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/**
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* @brief Assembles the element vector.
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*
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* @param el The finite element.
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* @param Trans The element transformation.
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* @param elfun The element function.
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* @param elvect The element vector to be assembled.
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*/
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virtual void AssembleElementVector(const mfem::FiniteElement &el, mfem::ElementTransformation &Trans, const mfem::Vector &elfun, mfem::Vector &elvect) override;
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/**
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* @brief Assembles the element gradient.
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*
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* @param el The finite element.
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* @param Trans The element transformation.
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* @param elfun The element function.
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* @param elmat The element matrix to be assembled.
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*/
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virtual void AssembleElementGrad (const mfem::FiniteElement &el, mfem::ElementTransformation &Trans, const mfem::Vector &elfun, mfem::DenseMatrix &elmat) override;
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private:
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serif::config::Config& m_config = serif::config::Config::getInstance();
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serif::probe::LogManager& m_logManager = serif::probe::LogManager::getInstance();
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quill::Logger* m_logger = m_logManager.getLogger("log");
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double m_polytropicIndex;
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double m_epsilon;
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static constexpr double m_regularizationRadius = 0.15; ///< Regularization radius for the epsilon function, used to avoid singularities in the power law.
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static constexpr double m_regularizationCoeff = 1.0/6.0; ///< Coefficient for the regularization term, used to ensure smoothness in the power law.
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};
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inline double dfmod(const double epsilon, const double n) {
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if (n == 0.0) {
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return 0.0;
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}
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if (n == 1.0) {
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return 1.0;
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}
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return n * std::pow(epsilon, n - 1.0);
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}
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inline double fmod(const double theta, const double n, const double epsilon) {
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if (n == 0.0) {
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return 1.0;
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}
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// For n != 0
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const double y_prime_at_epsilon = dfmod(epsilon, n); // Uses the robust dfmod
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const double y_at_epsilon = std::pow(epsilon, n); // epsilon^n
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// f_mod(theta) = y_at_epsilon + y_prime_at_epsilon * (theta - epsilon)
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return y_at_epsilon + y_prime_at_epsilon * (theta - epsilon);
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}
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} // namespace polyMFEMUtils
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} // namespace polytrope
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} // namespace serif
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