vector_fold.hpp
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1 /*!
2  * \brief Kernels for folding vector expressions
3  *
4  * \author O. Krause
5  * \date 2016
6  *
7  *
8  * \par Copyright 1995-2015 Shark Development Team
9  *
10  * <BR><HR>
11  * This file is part of Shark.
12  * <http://image.diku.dk/shark/>
13  *
14  * Shark is free software: you can redistribute it and/or modify
15  * it under the terms of the GNU Lesser General Public License as published
16  * by the Free Software Foundation, either version 3 of the License, or
17  * (at your option) any later version.
18  *
19  * Shark is distributed in the hope that it will be useful,
20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22  * GNU Lesser General Public License for more details.
23  *
24  * You should have received a copy of the GNU Lesser General Public License
25  * along with Shark. If not, see <http://www.gnu.org/licenses/>.
26  *
27  */
28 #ifndef REMORA_KERNELS_DEFAULT_VECTOR_FOLD_HPP
29 #define REMORA_KERNELS_DEFAULT_VECTOR_FOLD_HPP
30 
31 #include "../../expression_types.hpp"
32 
33 namespace remora{namespace bindings{
34 template<class F, class V>
35 void vector_fold(vector_expression<V, cpu_tag> const& v, typename F::result_type& value, dense_tag) {
36  F f;
37  std::size_t size = v().size();
38  for(std::size_t i = 0; i != size; ++i){
39  value = f(value,v()(i));
40  }
41 }
42 
43 template<class F, class V>
44 void vector_fold(vector_expression<V, cpu_tag> const& v, typename F::result_type& value, sparse_tag) {
45  F f;
46  std::size_t nnz = 0;
47  auto iter = v().begin();
48  auto end = v().end();
49  for(;iter != end;++iter,++nnz){
50  value = f(value,*iter);
51  }
52  //apply final operator f(0,v)
53  if(nnz != v().size())
54  value = f(value, 0);
55 }
56 
57 }}
58 #endif