1 files changed, 55 insertions, 0 deletions
diff --git a/include/phat/algorithms/row_reduction.h b/include/phat/algorithms/row_reduction.h
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+++ b/include/phat/algorithms/row_reduction.h
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+/*  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 <http://www.gnu.org/licenses/>. */
+
+#pragma once
+
+#include <phat/helpers/misc.h>
+#include <phat/boundary_matrix.h>
+
+namespace phat {
+    class row_reduction {
+    public:
+        template< typename Representation >
+        void operator() ( boundary_matrix< Representation >& boundary_matrix ) {
+            
+            const index nr_columns = boundary_matrix.get_num_cols();
+            std::vector< std::vector< index > > lowest_one_lookup( nr_columns );
+            
+            for( index cur_col = nr_columns - 1; cur_col >= 0; cur_col-- ) {
+                if( !boundary_matrix.is_empty( cur_col ) )
+                    lowest_one_lookup[ boundary_matrix.get_max_index( cur_col ) ].push_back( cur_col );
+                
+                if( !lowest_one_lookup[ cur_col ].empty() ) {
+                    boundary_matrix.clear( cur_col );
+                    std::vector< index >& cols_with_cur_lowest = lowest_one_lookup[ cur_col ];
+                    index source = *min_element( cols_with_cur_lowest.begin(), cols_with_cur_lowest.end() );
+                    for( index idx = 0; idx < (index)cols_with_cur_lowest.size(); idx++ ) {
+                        index target = cols_with_cur_lowest[ idx ];
+                        if( target != source && !boundary_matrix.is_empty( target ) ) {
+                            boundary_matrix.add_to( source, target );     
+                            if( !boundary_matrix.is_empty( target ) ) {
+                                index lowest_one_of_target = boundary_matrix.get_max_index( target );
+                                lowest_one_lookup[ lowest_one_of_target ].push_back( target );
+                            }
+                        } 
+                    }
+                }
+            }
+        }
+    };
+}
+\ No newline at end of file