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root.hh
1 // Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE)
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25 
26 #ifndef MLN_METAL_MATH_ROOT_HH
27 # define MLN_METAL_MATH_ROOT_HH
28 
36 # include <mln/metal/math/pow.hh>
37 
38 
39 # define mlc_root(N,X) mln::metal::math::root<( N ),( X )>
40 
41 
42 namespace mln
43 {
44 
45  namespace metal
46  {
47 
48  namespace math
49  {
50 
51  namespace impl
52  {
53 
54  template <unsigned n, unsigned x,
55  unsigned lo = 1, unsigned hi = x>
56  struct root
57  {
58  enum {
59  mid = (lo + hi + 1) / 2,
60  val_lo = root<n, x, lo, mid-1>::value,
61  val_hi = root<n, x, mid, hi>::value
62  };
63  enum { value = x < mlc_pow_int(mid, n) ? val_lo : val_hi };
64  };
65 
66  template<unsigned n, unsigned x, unsigned m>
67  struct root<n, x, m, m>
68  {
69  enum { value = m }; // Found.
70  };
71 
72  } // end of namespace mln::metal::math::impl
73 
74  template <unsigned n, unsigned x>
75  struct root : bool_<(n != 0)>::check_t
76  {
77  enum { value = impl::root<n,x>::value,
78  reminder = x - mlc_pow_int(value, n) };
79  };
80 
81  template <unsigned n>
82  struct root<n, 0> : bool_<(n != 0)>::check_t
83  {
84  enum { value = 0,
85  reminder = 0};
86  };
87 
88  } // end of namespace mln::metal::math
89 
90  } // end of namespace mln::metal
91 
92 } // end of namespace mln
93 
94 
95 #endif // ! MLN_METAL_MATH_ROOT_HH