Method DiffJacobi

fem/coefficient.cpp:4774–4806

  shared_ptr<CoefficientFunction> DiffJacobi (const CoefficientFunction * var, T_DJC & cache) const override
  {
    auto thisptr = const_pointer_cast<CoefficientFunction>(this->shared_from_this());
    if (cache.find(thisptr) != cache.end())
      return cache[thisptr];
    
    if (this == var)
      return IdentityCF(Dimensions());
    
    Array<int> dimres { this->Dimensions() };
    dimres += var->Dimensions();
    
    auto diffc1 = c1->DiffJacobi (var, cache);

    int vardim = var->Dimension();
    Array<int> vardims = Array<int> (var->Dimensions());
    Array<int> dist(vardims.Size());
    int prod = 1;
    for (int i = dist.Size()-1; i >= 0; i--)
      {
        dist[i] = prod;
        prod *= vardims[i];
      }
    Array<int> firstdist { this -> dist };
    for (auto & fd : firstdist)
      fd *= vardim;
      
    Array<int> alldist { firstdist + dist };
    
    auto res = MakeSubTensorCoefficientFunction(diffc1, first*vardim, std::move(dimres), std::move(alldist));
    cache[thisptr] = res;
    return res;
  }  
  

  virtual void NonZeroPattern (const class ProxyUserData & ud,