mathEvaluator.cpp

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// Gmsh - Copyright (C) 1997-2022 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file in the Gmsh root directory for license information.
// Please report all issues on https://gitlab.onelab.info/gmsh/gmsh/issues.
 
#include "mathEvaluator.h"
 
#if defined(HAVE_MATHEX)
 
mathEvaluator::mathEvaluator(std::vector<std::string> &expressions,
                             const std::vector<std::string> &variables)
{
  static std::string lastError;
 
  _expressions.resize(expressions.size());
  _variables.resize(variables.size(), 0.);
  bool error = false;
  for(std::size_t i = 0; i < expressions.size(); i++) {
    _expressions[i] = new smlib::mathex();
    for(std::size_t j = 0; j < variables.size(); j++)
      _expressions[i]->addvar(variables[j], &_variables[j]);
    try {
      _expressions[i]->expression(expressions[i]);
      _expressions[i]->parse();
    } catch(smlib::mathex::error &e) {
      if(e.what() + expressions[i] != lastError) {
        lastError = e.what() + expressions[i];
        Msg::Error(e.what());
        std::string pos(_expressions[i]->stopposition(), ' ');
        pos.push_back('^');
        Msg::Error(expressions[i].c_str());
        Msg::Error(pos.c_str());
      }
      error = true;
    }
  }
  if(error) {
    for(std::size_t i = 0; i < _expressions.size(); i++)
      delete(_expressions[i]);
    _expressions.clear();
    expressions.clear();
  }
}
 
mathEvaluator::~mathEvaluator()
{
  for(std::size_t i = 0; i < _expressions.size(); i++) delete(_expressions[i]);
}
 
bool mathEvaluator::eval(const std::vector<double> &values,
                         std::vector<double> &res)
{
  if(values.size() != _variables.size()) {
    Msg::Error("Given %d value(s) for %d variable(s)", values.size(),
               _variables.size());
    return false;
  }
 
  if(res.size() != _expressions.size()) {
    Msg::Error("Given %d result(s) for %d expression(s)", res.size(),
               _expressions.size());
    return false;
  }
 
  for(std::size_t i = 0; i < values.size(); i++) _variables[i] = values[i];
 
  for(std::size_t i = 0; i < _expressions.size(); i++) {
    try {
      res[i] = _expressions[i]->eval();
    } catch(smlib::mathex::error &e) {
      Msg::Error(e.what());
      double eps = 1.e-20;
      for(std::size_t j = 0; j < values.size(); j++)
        _variables[j] = values[j] + eps;
      try {
        res[i] = _expressions[i]->eval();
      } catch(smlib::mathex::error &e2) {
        Msg::Error(e2.what());
        return false;
      }
    }
  }
  return true;
}
 
#endif