text: // Copyright 2018 The Simons Foundation, Inc. - All Rights Reserved.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //    http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  /* author: Alexander Wietek, 2018/10/22 */
  
  #ifndef EXTERNAL_IETL_IETL_VECTORSPACE_H_
  #define EXTERNAL_IETL_IETL_VECTORSPACE_H_
  
  #include <ietl/complex.h>
  #include <ietl/traits.h>
  #include <Eigen/SparseCore>
  
  namespace ietl {
  
  template <class TCoeffs>
  class vectorspace {
   public:
    using vector_type = Eigen::Matrix<TCoeffs, Eigen::Dynamic, 1>;
    using real_type = typename real_type<TCoeffs>::type;
    using size_type = size_t;
    using scalar_type = TCoeffs;
  
    explicit vectorspace(size_type dim) : dim_(dim) {}
  
    inline size_type vec_dimension() const { return dim_; }
  
    vector_type new_vector() const {
      vector_type v = vector_type::Zero(dim_);
      return v;
    }
  
    void project(vector_type&) const {}
  
   private:
    size_type dim_;
  };
  
  template <class VS>
  void project(typename vectorspace_traits<VS>::vector_type& v, const VS& vs) {
    vs.project(v);
  }
  
  template <class VS>
  typename ietl::vectorspace_traits<VS>::vector_type new_vector(const VS& vs) {
    return vs.new_vector();
  }
  
  template <class VS>
  typename ietl::vectorspace_traits<VS>::size_type vec_dimension(const VS& vs) {
    return vs.vec_dimension();
  }
  }  // namespace ietl
  
  #endif  // EXTERNAL_IETL_IETL_VECTORSPACE_H_
  