boost/units/pow.hpp

   1 // Boost.Units - A C++ library for zero-overhead dimensional analysis and
   2 // unit/quantity manipulation and conversion
   3 //
   4 // Copyright (C) 2003-2008 Matthias Christian Schabel
   5 // Copyright (C) 2008 Steven Watanabe
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See
   8 // accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10
  11 #ifndef BOOST_UNITS_POW_HPP
  12 #define BOOST_UNITS_POW_HPP
  13
  14 #include <boost/math_fwd.hpp>
  15 #include <boost/type_traits/is_integral.hpp>
  16
  17 #include <boost/units/operators.hpp>
  18 #include <boost/units/static_rational.hpp>
  19 #include <boost/units/detail/static_rational_power.hpp>
  20
  21 /// \file
  22 /// \brief Raise values to exponents known at compile-time
  23
  24 namespace boost {
  25
  26 namespace units {
  27
  28 /// raise a value to a @c static_rational power
  29 template<class Rat,class Y>
  30 inline typename power_typeof_helper<Y,Rat>::type
  31 pow(const Y& x)
  32 {
  33     return power_typeof_helper<Y,Rat>::value(x);
  34 }
  35
  36 /// raise a value to an integer power
  37 template<long N,class Y>
  38 inline typename power_typeof_helper<Y,static_rational<N> >::type
  39 pow(const Y& x)
  40 {
  41     return power_typeof_helper<Y,static_rational<N> >::value(x);
  42 }
  43
  44 #ifndef BOOST_UNITS_DOXYGEN
  45
  46 /// raise @c T to a @c static_rational power
  47 template<class T, long N,long D>
  48 struct power_typeof_helper<T, static_rational<N,D> >
  49 {
  50     typedef typename mpl::if_<boost::is_integral<T>, double, T>::type internal_type;
  51     typedef detail::static_rational_power_impl<static_rational<N, D>, internal_type> impl;
  52     typedef typename impl::type type;
  53
  54     static type value(const T& x)
  55     {
  56         return impl::call(x);
  57     }
  58 };
  59
  60 /// raise @c float to a @c static_rational power
  61 template<long N,long D>
  62 struct power_typeof_helper<float, static_rational<N,D> >
  63 {
  64     // N.B.  pathscale doesn't accept inheritence for some reason.
  65     typedef power_typeof_helper<double, static_rational<N,D> > base;
  66     typedef typename base::type type;
  67     static type value(const double& x)
  68     {
  69         return base::value(x);
  70     }
  71 };
  72
  73 #endif
  74
  75 /// take the @c static_rational root of a value
  76 template<class Rat,class Y>
  77 typename root_typeof_helper<Y,Rat>::type
  78 root(const Y& x)
  79 {
  80     return root_typeof_helper<Y,Rat>::value(x);
  81 }
  82
  83 /// take the integer root of a value
  84 template<long N,class Y>
  85 typename root_typeof_helper<Y,static_rational<N> >::type
  86 root(const Y& x)
  87 {
  88     return root_typeof_helper<Y,static_rational<N> >::value(x);
  89 }
  90
  91 #ifndef BOOST_UNITS_DOXYGEN
  92
  93 /// take @c static_rational root of an @c T
  94 template<class T, long N,long D>
  95 struct root_typeof_helper<T,static_rational<N,D> >
  96 {
  97     // N.B.  pathscale doesn't accept inheritence for some reason.
  98     typedef power_typeof_helper<T, static_rational<D,N> > base;
  99     typedef typename base::type type;
 100     static type value(const T& x)
 101     {
 102         return(base::value(x));
 103     }
 104 };
 105
 106 #endif
 107
 108 } // namespace units
 109
 110 } // namespace boost
 111
 112 #endif // BOOST_UNITS_STATIC_RATIONAL_HPP