/usr/include/CGAL/ipower.h is in libcgal-dev 4.11-2build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | // Copyright (c) 2008 Max-Planck-Institute Saarbruecken (Germany).
// 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 Lesser 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 Hemmer
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
#ifndef CGAL_IPOWER_H
#define CGAL_IPOWER_H
#include <CGAL/assertions.h>
namespace CGAL {
template <typename NT>
inline
NT ipower(const NT& base, int expn) {
// compute base^expn using square-and-multiply
CGAL_precondition(expn >= 0);
// handle trivial cases efficiently
if (expn == 0) return NT(1);
if (expn == 1) return base;
// find the most significant non-zero bit of expn
int e = expn, msb = 0;
while (e >>= 1) msb++;
// computing base^expn by square-and-multiply
NT res = base;
int b = 1<<msb;
while (b >>= 1) { // is there another bit right of what we saw so far?
res *= res;
if (expn & b) res *= base;
}
return res;
}
template <typename NT>
inline
NT ipower(const NT& base, long expn) {
// compute base^expn using square-and-multiply
CGAL_precondition(expn >= 0);
// handle trivial cases efficiently
if (expn == 0) return NT(1);
if (expn == 1) return base;
// find the most significant non-zero bit of expn
long e = expn, msb = 0;
while (e >>= 1) msb++;
// computing base^expn by square-and-multiply
NT res = base;
long b = 1L<<msb;
while (b >>= 1) { // is there another bit right of what we saw so far?
res *= res;
if (expn & b) res *= base;
}
return res;
}
} //namespace CGAL
#endif // CGAL_IPOWER_H
|