mirror of https://github.com/CGAL/cgal
71 lines
1.9 KiB
C++
71 lines
1.9 KiB
C++
// Copyright (c) 2006-2008 Max-Planck-Institute Saarbruecken (Germany).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 3 of the License,
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// or (at your option) any later version.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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//
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//
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// Author(s) : Michael Hemmer <hemmer@mpi-inf.mpg.de>
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//
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// =============================================================================
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#ifndef CGAL_PRIMES_H
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#define CGAL_PRIMES_H
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#include <CGAL/basic.h>
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namespace CGAL {
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namespace internal {
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CGAL_EXPORT extern const int primes[2000];
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static inline
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int get_next_lower_prime(int current_prime){
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bool is_prime = false;
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int i;
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CGAL_precondition_msg(current_prime != 2 ," primes definitely exhausted ");
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if((current_prime <= 7) && (current_prime > 2)){
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if(current_prime <= 5){
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if(current_prime == 3)
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return 2;
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return 3;
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}
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return 5;
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}
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for(i=current_prime-2;(i>1 && !is_prime);i=i-2){
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int r = 1;
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for(int j=3; (j <= i/2 && (r != 0)); j++){
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r = i % j;
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// std::cout<<"i " <<i<<std::endl;
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// std::cout<<"j " <<j<<std::endl;
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// std::cout<<"i%j " <<i%j<<std::endl;
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if(j==i/2 && r != 0)
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is_prime = true;
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}
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}
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// CGAL_precondition_msg(is_prime," primes definitely exhausted ");
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return i+2;
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}
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}
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}
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#ifdef CGAL_HEADER_ONLY
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#include <CGAL/primes_impl.h>
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#endif // CGAL_HEADER_ONLY
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#endif // CGAL_PRIMES_H
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