/usr/include/dune/common/power.hh is in libdune-common-dev 2.4.1-1.
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_COMMON_POWER_HH
#define DUNE_COMMON_POWER_HH
/** \file
\brief Various implementations of the power function for run-time and static arguments
*/
namespace Dune {
/** @addtogroup Common
@{
*/
//! Calculates m^p at compile time
template <int m, int p>
struct StaticPower
{
/** \brief power stores m^p */
enum { power = (m * StaticPower<m,p-1>::power ) };
};
//! end of recursion via specialization
template <int m>
struct StaticPower< m , 0>
{
/** \brief m^0 = 1 */
enum { power = 1 };
};
#ifndef DOXYGEN
template <int p, bool odd = p%2>
struct PowerImp {};
#endif
/** \brief Compute power for a run-time mantissa and a compile-time integer exponent
*
* Does some magic to create efficient code. Not benchmarked AFAIK.
*
* \tparam p The exponent
*/
template <int p>
struct Power
{
template <typename T>
static T eval(const T & a)
{
return PowerImp<p>::eval(a);
}
};
#ifndef DOXYGEN
template <int p>
struct PowerImp<p,false>
{
template <typename T>
static T eval(const T & a)
{
T t = Power<p/2>::eval(a);
return t*t;
}
};
template <int p>
struct PowerImp<p,true>
{
template <typename T>
static T eval(const T & a)
{
return a*Power<p-1>::eval(a);;
}
};
template <>
struct PowerImp<1,true>
{
template <typename T>
static T eval(const T & a)
{
return a;
}
};
#endif
}
#endif
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