From c817c81d9d79fe77b0729216b7db5a7eab56a23c Mon Sep 17 00:00:00 2001 From: "ulrich.bauer@gmail.com" Date: Thu, 28 Feb 2013 19:31:04 +0000 Subject: initial checkin git-svn-id: https://phat.googlecode.com/svn/trunk@2 8e3bb3c2-eed4-f18f-5264-0b6c94e6926d --- include/phat/algorithms/twist_reduction.h | 50 +++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 include/phat/algorithms/twist_reduction.h (limited to 'include/phat/algorithms/twist_reduction.h') diff --git a/include/phat/algorithms/twist_reduction.h b/include/phat/algorithms/twist_reduction.h new file mode 100644 index 0000000..b9aae08 --- /dev/null +++ b/include/phat/algorithms/twist_reduction.h @@ -0,0 +1,50 @@ +/* Copyright 2013 IST Austria + Contributed by: Ulrich Bauer, Michael Kerber, Jan Reininghaus + + This file is part of PHAT. + + PHAT is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + PHAT 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 Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with PHAT. If not, see . */ + +#pragma once + +#include +#include + +namespace phat { + class twist_reduction { + public: + template< typename Representation > + void operator () ( boundary_matrix< Representation >& boundary_matrix ) { + + const index nr_columns = boundary_matrix.get_num_cols(); + std::vector< index > lowest_one_lookup( nr_columns, -1 ); + + for( index cur_dim = boundary_matrix.get_max_dim(); cur_dim >= 1 ; cur_dim-- ) { + for( index cur_col = 0; cur_col < nr_columns; cur_col++ ) { + if( boundary_matrix.get_dim( cur_col ) == cur_dim ) { + index lowest_one = boundary_matrix.get_max_index( cur_col ); + while( lowest_one != -1 && lowest_one_lookup[ lowest_one ] != -1 ) { + boundary_matrix.add_to( lowest_one_lookup[ lowest_one ], cur_col ); + lowest_one = boundary_matrix.get_max_index( cur_col ); + } + if( lowest_one != -1 ) { + lowest_one_lookup[ lowest_one ] = cur_col; + boundary_matrix.clear( lowest_one ); + } + } + } + } + } + }; +} -- cgit v1.2.3