Dg_minus_Dg.hpp

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/* Subtracts a Dg from a Dg, yielding a Dg or
   Tensor3. */
 
#pragma once
 
namespace FTensor
{
  /* A(i,j,k)-B(i,j,k)->Dg */
 
  template <class A, class B, class T, class U, int Dim01, int Dim2, char i,
            char j, char k>
  class Dg_minus_Dg
  {
    Dg_Expr<A, T, Dim01, Dim2, i, j, k> iterA;
    Dg_Expr<B, U, Dim01, Dim2, i, j, k> iterB;
 
  public:
    typename promote<T, U>::V
    operator()(const int N1, const int N2, const int N3) const
    {
      return iterA(N1, N2, N3) - iterB(N1, N2, N3);
    }
 
    Dg_minus_Dg(const Dg_Expr<A, T, Dim01, Dim2, i, j, k> &a,
                const Dg_Expr<B, U, Dim01, Dim2, i, j, k> &b)
        : iterA(a), iterB(b)
    {}
  };
 
  template <class A, class B, class T, class U, int Dim01, int Dim2, char i,
            char j, char k>
  Dg_Expr<Dg_minus_Dg<A, B, T, U, Dim01, Dim2, i, j, k>,
          typename promote<T, U>::V, Dim01, Dim2, i, j, k>
  operator-(const Dg_Expr<A, T, Dim01, Dim2, i, j, k> &a,
            const Dg_Expr<B, U, Dim01, Dim2, i, j, k> &b)
  {
    using TensorExpr = Dg_minus_Dg<A, B, T, U, Dim01, Dim2, i, j, k>;
    return Dg_Expr<TensorExpr, typename promote<T, U>::V, Dim01, Dim2, i, j, k>(
      TensorExpr(a, b));
  }
 
  /* A(i,j,k)-B(k,j,i)->Tensor3 */
 
  template <class A, class B, class T, class U, int Dim, char i, char j, char k>
  class Dg_minus_Dg_02
  {
    Dg_Expr<A, T, Dim, Dim, i, j, k> iterA;
    Dg_Expr<B, U, Dim, Dim, k, j, i> iterB;
 
  public:
    typename promote<T, U>::V
    operator()(const int N1, const int N2, const int N3) const
    {
      return iterA(N1, N2, N3) - iterB(N3, N2, N1);
    }
 
    Dg_minus_Dg_02(const Dg_Expr<A, T, Dim, Dim, i, j, k> &a,
                   const Dg_Expr<B, U, Dim, Dim, k, j, i> &b)
        : iterA(a), iterB(b)
    {}
  };
 
  template <class A, class B, class T, class U, int Dim, char i, char j, char k>
  Tensor3_Expr<Dg_minus_Dg_02<A, B, T, U, Dim, i, j, k>,
               typename promote<T, U>::V, Dim, Dim, Dim, i, j, k>
  operator-(const Dg_Expr<A, T, Dim, Dim, i, j, k> &a,
            const Dg_Expr<B, U, Dim, Dim, k, j, i> &b)
  {
    using TensorExpr = Dg_minus_Dg_02<A, B, T, U, Dim, i, j, k>;
    return Tensor3_Expr<TensorExpr, typename promote<T, U>::V, Dim, Dim, Dim,
                        i, j, k>(TensorExpr(a, b));
  }
}