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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_GCD_HH
#define DUNE_GCD_HH
#include "helpertemplates.hh"
namespace Dune
{
/**
* @addtogroup Common
* @{
*/
/**
* @file
* This file provides template constructs for calculation the
* greatest common divisor.
*/
/**
* @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()
{
IsTrue<b<a>::yes();
IsTrue<0<b>::yes();
}
/**
* @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;
};
/**
* @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