Power.h

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/*
 * Copyright (C) 2012 by
 *   MetraLabs GmbH (MLAB), GERMANY
 * and
 *   Neuroinformatics and Cognitive Robotics Labs (NICR) at TU Ilmenau, GERMANY
 * All rights reserved.
 *
 * Contact: info@mira-project.org
 *
 * Commercial Usage:
 *   Licensees holding valid commercial licenses may use this file in
 *   accordance with the commercial license agreement provided with the
 *   software or, alternatively, in accordance with the terms contained in
 *   a written agreement between you and MLAB or NICR.
 *
 * GNU General Public License Usage:
 *   Alternatively, this file may be used under the terms of the GNU
 *   General Public License version 3.0 as published by the Free Software
 *   Foundation and appearing in the file LICENSE.GPL3 included in the
 *   packaging of this file. Please review the following information to
 *   ensure the GNU General Public License version 3.0 requirements will be
 *   met: http://www.gnu.org/copyleft/gpl.html.
 *   Alternatively you may (at your option) use any later version of the GNU
 *   General Public License if such license has been publicly approved by
 *   MLAB and NICR (or its successors, if any).
 *
 * IN NO EVENT SHALL "MLAB" OR "NICR" BE LIABLE TO ANY PARTY FOR DIRECT,
 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
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 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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 */

#ifndef _MIRA_POWER_H_
#define _MIRA_POWER_H_

#include <cmath>

namespace mira {


namespace detail {

template <typename T, int N>
struct PowerComputer
{
    inline static T eval(T base) {
        return PowerComputer<T,N-1>::eval(base)*base;
    }
};

template <typename T>
struct PowerComputer<T,1>
{
    inline static T eval(T base) {
        return base;
    }
};

template <typename T>
struct PowerComputer<T,0>
{
    inline static T eval(T base) {
        return 1;
    }
};

}

template <int exponent, typename T>
inline T pow(T base)
{
    return detail::PowerComputer<T,exponent>::eval(base);
}

template <typename T>
inline T pow2(T base)
{
    return base*base;
}

template <typename T>
inline T pow3(T base)
{
    return base*base*base;
}


template<int base, int exponent>
struct TPower {
    enum {
        value = TPower<base,exponent-1>::value * base
    };
};

template<int base>
struct TPower<base,0> {
    enum {
        value = 1
    };
};



// two workarounds for those guys that use the old C pow(double,double) method -
// this now delegate those calls to the preferred std::pow() methods
template <typename T, typename U>
inline T pow(T base, U exponent)
{
    return std::pow(base,exponent);
}

template <typename T>
inline T pow(T base, T exponent)
{
    return std::pow(base,exponent);
}


} // namespace

#endif