Exchange.hh

Go to the documentation of this file.

/* 

    Cadabra: a field-theory motivated computer algebra system.
    Copyright (C) 2001-2014  Kasper Peeters <kasper.peeters@phi-sci.com>

   This program is free software: you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
*/

#pragma once

#include <vector>

#include "Storage.hh"

#include "properties/GammaMatrix.hh"
#include "properties/Spinor.hh"
#include "properties/Traceless.hh"
#include "properties/GammaTraceless.hh"
#include "properties/SelfCommutingBehaviour.hh"
#include "properties/CommutingBehaviour.hh"

namespace cadabra {

class exchange {
    public:
        struct identical_tensors_t {
                unsigned int                           number_of_indices;
                std::vector<Ex::sibling_iterator> tensors;
                std::vector<int>                       seq_numbers_of_first_indices;

                const SelfCommutingBehaviour *comm;
                const Spinor                 *spino;
                const TableauBase            *tab;
                const Traceless              *traceless;
                const GammaTraceless         *gammatraceless;
                int                           extra_sign;
        };

        // Obtain index exchange symmetries under tensor permutation. Returns 'false' if 
        // an identically zero expression is encountered.
        static int          collect_identical_tensors(const Properties& pr, Ex& tr, Ex::iterator it,
                                                                     std::vector<identical_tensors_t>& idts);
        static unsigned int possible_singlets(Ex&, Ex::iterator);
        static bool         get_node_gs(const Properties&, Ex&, Ex::iterator, std::vector<std::vector<int> >& );

//      static void get_index_gs(Ex::iterator, std::vector<std::vector<int> >& );

        struct tensor_type_t {
                nset_t::iterator name;
                unsigned int     number_of_indices;
        };

};

bool operator<(const exchange::tensor_type_t& one, const exchange::tensor_type_t& two);


}