/usr/include/CGAL/monotone_matrix_search.h is in libcgal-dev 4.2-5ubuntu1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 | // Copyright (c) 1998-2003 ETH Zurich (Switzerland).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
// 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.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
//
// Author(s) : Michael Hoffmann <hoffmann@inf.ethz.ch>
#ifndef CGAL_MONOTONE_MATRIX_SEARCH_H
#define CGAL_MONOTONE_MATRIX_SEARCH_H 1
#include <CGAL/Optimisation/assertions.h>
#include <vector>
#include <functional>
namespace CGAL {
template < class Matrix, class RandomAccessIterator >
inline
void
monotone_matrix_search(
const Matrix& M,
RandomAccessIterator t)
{
typedef typename Matrix::Value V;
monotone_matrix_search( M, t, std::less< V >());
} // monotone_matrix_search( M, t)
template < class Matrix,
class RandomAccessIterator,
class Compare_strictly >
void
monotone_matrix_search(
const Matrix& M,
RandomAccessIterator t,
const Compare_strictly& compare_strictly)
// Matrix has to define:
// o operator()( int, int) [access]
// o int number_of_columns(), int number_of_rows()
// o replace_column( int o, int n)
// o shrink_to_quadratic_size()
// o Matrix* extract_all_even_rows()
//
// Precondition: M is totally monotone
// M.number_of_rows() > 1 and
// RandomAccessIterator has value type int
//
// writes to t the positions (columns)
// of the row maxima of M
{
// divide
// ------
// get even rows of M:
Matrix* M_new = M.extract_all_even_rows();
CGAL_optimisation_assertion(
M_new->number_of_columns() == M.number_of_columns());
CGAL_optimisation_assertion(
M_new->number_of_rows() == 0 ||
M_new->number_of_rows() == ( M.number_of_rows() + 1) >> 1);
// reduce M_new to a quadratic matrix:
// table to store the reduction permutation:
// (incl. sentinel)
int* reduction_table = new int[ M_new->number_of_rows() + 1];
if ( M_new->number_of_rows() < M_new->number_of_columns()) {
// set sentinel:
reduction_table[M_new->number_of_rows()] =
M.number_of_columns() - 1;
_reduce_matrix( *M_new, reduction_table, compare_strictly);
CGAL_optimisation_assertion(
M_new->number_of_columns() == M_new->number_of_rows());
} // if ( M_new->number_of_rows() < M_new->number_of_columns())
else {
// no reduction -> reduction_table is identity table:
for ( int i1( 0); i1 < M_new->number_of_columns(); ++i1)
reduction_table[i1] = i1;
// set sentinel:
reduction_table[M_new->number_of_columns()] =
M_new->number_of_columns() - 1;
}
// recursion:
CGAL_optimisation_assertion(
M_new->number_of_rows() >= M_new->number_of_columns());
// table to store the rmax values of M_new:
// (incl. sentinel)
int* t_new = new int[M_new->number_of_rows() + 1];
t_new[M_new->number_of_rows()] = M_new->number_of_columns();
if ( M_new->number_of_rows() == 1)
// recursion anchor:
// we have just one element ==> no choice
t_new[0] = 0;
else
monotone_matrix_search( *M_new, t_new);
// and conquer
// -----------
int j( 0); // actual index in t
int j_new( 0); // actual index in t_new
do {
// even row ==> we know
*(t+j) = reduction_table[t_new[j_new++]];
if ( ++j >= M.number_of_rows())
break;
// odd row
// search *(t+j) between *(t+j-1) and t_new[j_new]:
*(t+j) = reduction_table[t_new[j_new]];
int j_tmp( *(t+j-1));
while ( j_tmp < reduction_table[t_new[j_new]]) {
if ( compare_strictly( M( j, t[j]), M( j, j_tmp)))
*(t+j) = j_tmp++;
else
++j_tmp;
}
} while ( ++j < M.number_of_rows());
delete M_new;
delete[] t_new;
delete[] reduction_table;
} // monotone_matrix_search( M, t)
template < class Matrix,
class RandomAccessIterator,
class Compare_strictly >
void
_reduce_matrix(
Matrix& M,
RandomAccessIterator t,
const Compare_strictly& compare_strictly)
// Matrix has to define:
// o operator()( int, int) [access]
// o int number_of_columns(), int number_of_rows()
// o replace_column( int o, int n)
// o shrink_to_quadratic_size()
// o Matrix* extract_all_even_rows()
//
// Precondition: M is totally monotone
// reduces M, i.e. deletes some columns that
// do not contain the maximum value of any row
// such that M becomes quadratic
// and returns for each column of the resulting
// matrix its column index in the original matrix
{
CGAL_optimisation_precondition(
M.number_of_columns() >= M.number_of_rows());
// active columns are 0, ..., j1, j2, ..., M.x_dim()-1
int j1( 0), j2( 1);
*t = 0;
while ( j2 - j1 < M.number_of_columns() - M.number_of_rows() + 1) {
if ( compare_strictly( M( j1, j1), M( j1, j2))) {
// delete column j1
if ( j1 > 0)
--j1;
else {
M.replace_column( 0, j2);
*t = j2++;
}
}
else {
if ( j1 < M.number_of_rows() - 1) {
// proceed
M.replace_column( ++j1, j2);
*(t+j1) = j2;
}
// else delete column j2
++j2;
}
} // while ( j2 - j1 <
// M.number_of_columns() - M.number_of_rows() + 1)
// M.number_of_columns() - M.number_of_rows() columns
// have been deleted, now move columns
// j2 .. M.number_of_columns()-1 to the first part
while ( j1 < M.number_of_rows() - 1) {
CGAL_optimisation_assertion( j2 < M.number_of_columns());
M.replace_column( ++j1, j2);
*(t+j1) = j2++;
}
M.shrink_to_quadratic_size();
} // _reduce_matrix( M, t)
} //namespace CGAL
#endif // ! (CGAL_MONOTONE_MATRIX_SEARCH_H)
// ----------------------------------------------------------------------------
// ** EOF
// ----------------------------------------------------------------------------
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