quantity.hpp

/**
 * \file quantity.hpp
 *
 * \brief   Zero-overhead dimensional analysis and unit/quantity manipulation and conversion.
 * \author  Michael S. Kenniston, Martin Moene
 * \date    7 September 2013
 * \since   0.4
 *
 * Copyright 2013 Universiteit Leiden. All rights reserved.
 *
 * Copyright (c) 2001 by Michael S. Kenniston.  For the most
 * recent version check www.xnet.com/~msk/quantity.  Permission is granted
 * to use this code without restriction so long as this copyright
 * notice appears in all source files.
 *
 * This code is provided as-is, with no warrantee of correctness.
 *
 * Distributed under the Boost Software License, Version 1.0. (See accompanying
 * file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 */

/*
 * Unless otherwise specified, the definitions of all units in this
 * file are from NIST Special Publication 811, found online at
 * http://physics.nist.gov/Document/sp811.pdf
 * Other sources: OED = Oxford English Dictionary
 */

#ifndef PHYS_UNITS_QUANTITY_HPP_INCLUDED
#define PHYS_UNITS_QUANTITY_HPP_INCLUDED

#include <cmath>
#include <cstdlib>
#include <utility>  // std::declval

/// namespace phys.

namespace phys {

/// namespace units.

namespace units {

#ifdef PHYS_UNITS_REP_TYPE
   using Rep = PHYS_UNITS_REP_TYPE;
#else
   using Rep = double;
#endif

/*
 * declare now, define later.
 */
template< typename Dims, typename T = Rep >
class quantity;

/**
 * We could drag dimensions around individually, but it's much more convenient to package them.
 */
template< int D1, int D2, int D3, int D4 = 0, int D5 = 0, int D6 = 0, int D7 = 0 >
struct dimensions
{
    enum
    {
        dim1 = D1,
        dim2 = D2,
        dim3 = D3,
        dim4 = D4,
        dim5 = D5,
        dim6 = D6,
        dim7 = D7,