/usr/include/dune/common/gcd.hh is in libdune-common-dev 2.5.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_GCD_HH
#define DUNE_GCD_HH
namespace Dune
{
/**
* @addtogroup Common
* @{
*/
/**
* @file
* \brief Statically compute the greatest common divisor of two integers
*/
#ifndef DOXYGEN
/**
* @brief Helper for calculating the gcd.
*/
template<long a, long b, bool bo>
struct GcdHelper
{};
template<long a, long b>
struct GcdHelper<a,b,true>
{
/**
* @brief Check that a>b.
*/
static void conceptCheck()
{
static_assert(b<a, "b<a must hold!");
static_assert(0<b, "b must be positive");
}
/**
* @brief The greatest common divisor of the numbers a and b.
*/
const static long gcd = GcdHelper<b,a%b,true>::gcd;
};
template<long a, long b>
struct GcdHelper<a,b,false>
{
/**
* @brief The greatest common divisor of the numbers a and b.
*/
const static long gcd = GcdHelper<b,a,true>::gcd;
};
template<long a>
struct GcdHelper<a,0,true>
{
const static long gcd=a;
};
#endif
/**
* @brief Calculator of the greatest common divisor.
*/
template<long a, long b>
struct Gcd
{
/**
* @brief The greatest common divisior of a and b. */
const static long value = GcdHelper<a,b,(a>b)>::gcd;
};
/**
* @}
*/
}
#endif
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