ExprNode.cc

/*
 * Copyright © 2007-2025 Dynare Team
 *
 * This file is part of Dynare.
 *
 * Dynare is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Dynare is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Dynare.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <algorithm>
#include <cassert>
#include <cmath>
#include <iostream>
#include <limits>
#include <numbers>
#include <numeric>
#include <ranges>
#include <utility>

#include "DataTree.hh"
#include "ExprNode.hh"
#include "ModFile.hh"

ExprNode::ExprNode(DataTree& datatree_arg, int idx_arg) : datatree {datatree_arg}, idx {idx_arg}
{
}

expr_t
ExprNode::getDerivative(int deriv_id)
{
  if (!preparedForDerivation)
    prepareForDerivation();

  // Return zero if derivative is necessarily null (using symbolic a priori)
  if (!non_null_derivatives.contains(deriv_id))
    return datatree.Zero;

  // If derivative is stored in cache, use the cached value, otherwise compute it (and cache it)
  if (auto it2 = derivatives.find(deriv_id); it2 != derivatives.end())
    return it2->second;
  else
    {
      expr_t d = computeDerivative(deriv_id);
      derivatives[deriv_id] = d;
      return d;
    }
}

expr_t
ExprNode::getChainRuleDerivative(int deriv_id, const map<int, BinaryOpNode*>& recursive_variables,
                                 unordered_map<expr_t, set<int>>& non_null_chain_rule_derivatives,
                                 unordered_map<expr_t, map<int, expr_t>>& cache)
{
  if (!non_null_chain_rule_derivatives.contains(this))
    prepareForChainRuleDerivation(recursive_variables, non_null_chain_rule_derivatives);

  // Return zero if derivative is necessarily null (using symbolic a priori)
  if (!non_null_chain_rule_derivatives.at(this).contains(deriv_id))
    return datatree.Zero;