Tensor2_symmetric_and_Tensor2_symmetric.hpp

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/* Multiply a Tensor2_symmetric and a Tensor2_symmetric together but
   don't contract, yielding a Tensor2_symmetric. */
 
/* A(i,j) & B(i,j) -> Tensor2_symmetric */
 
#pragma once
 
namespace FTensor
{
  /* Base Template */
  template <class A, class B, class T, class U, int Dim_0, int Dim_1, char i0,
            char j0, char i1, char j1>
  class Tensor2_symmetric_and_Tensor2_symmetric
  {};
 
  template <class A, class B, class T, class U, int Dim, char i, char j>
  class Tensor2_symmetric_and_Tensor2_symmetric<A, B, T, U, Dim, Dim, i, j, i,
                                                j>
  {
    Tensor2_symmetric_Expr<A, T, Dim, i, j> iterA;
    Tensor2_symmetric_Expr<B, U, Dim, i, j> iterB;
 
  public:
    typename promote<T, U>::V operator()(const int N1, const int N2) const
    {
      return iterA(N1, N2) * iterB(N1, N2);
    }
 
    Tensor2_symmetric_and_Tensor2_symmetric(
      const Tensor2_symmetric_Expr<A, T, Dim, i, j> &a,
      const Tensor2_symmetric_Expr<B, U, Dim, i, j> &b)
        : iterA(a), iterB(b)
    {}
  };
 
  /* A(i,j) & B(j,i) -> Tensor2_symmetric */
 
  template <class A, class B, class T, class U, int Dim, char i, char j>
  class Tensor2_symmetric_and_Tensor2_symmetric<A, B, T, U, Dim, Dim, i, j, j,
                                                i>
  {
    Tensor2_symmetric_Expr<A, T, Dim, i, j> iterA;
    Tensor2_symmetric_Expr<B, U, Dim, j, i> iterB;
 
  public:
    typename promote<T, U>::V operator()(const int N1, const int N2) const
    {
      return iterA(N1, N2) * iterB(N2, N1);
    }
 
    Tensor2_symmetric_and_Tensor2_symmetric(
      const Tensor2_symmetric_Expr<A, T, Dim, i, j> &a,
      const Tensor2_symmetric_Expr<B, U, Dim, j, i> &b)
        : iterA(a), iterB(b)
    {}
  };
 
  template <class A, class B, class T, class U, int Dim_0, int Dim_1, char i0,
            char j0, char i1, char j1>
  Tensor2_symmetric_Expr<Tensor2_symmetric_and_Tensor2_symmetric<
                           A, B, T, U, Dim_0, Dim_1, i0, j0, i1, j1>,
                         typename promote<T, U>::V, Dim_0, i0, j0>
  operator&(const Tensor2_symmetric_Expr<A, T, Dim_0, i0, j0> &a,
            const Tensor2_symmetric_Expr<B, U, Dim_1, i1, j1> &b)
  {
    using TensorExpr
      = Tensor2_symmetric_and_Tensor2_symmetric<A, B, T, U, Dim_0, Dim_1, i0,
                                                j0, i1, j1>;
    static_assert(
      !std::is_empty<TensorExpr>::value,
      "Indexes or Dimensions are not compatible with the & operator");
    return Tensor2_symmetric_Expr<TensorExpr, typename promote<T, U>::V, Dim_0,
                                  i0, j0>(TensorExpr(a, b));
  }
}