libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // <numeric>
  12
  13 // template <class _Float>
  14 // _Tp midpoint(_Float __a, _Float __b) noexcept
  15 //
  16
  17 #include <numeric>
  18 #include <cassert>
  19
  20 #include "test_macros.h"
  21 #include "fp_compare.h"
  22
  23 //  Totally arbitrary picks for precision
  24 template <typename T>
  25 constexpr T fp_error_pct();
  26
  27 template <>
  28 constexpr float fp_error_pct<float>() { return 1.0e-4f; }
  29
  30 template <>
  31 constexpr double fp_error_pct<double>() { return 1.0e-12; }
  32
  33 template <>
  34 constexpr long double fp_error_pct<long double>() { return 1.0e-13l; }
  35
  36
  37 template <typename T>
  38 void fp_test()
  39 {
  40     ASSERT_SAME_TYPE(T, decltype(std::midpoint(T(), T())));
  41     ASSERT_NOEXCEPT(             std::midpoint(T(), T()));
  42
  43     constexpr T maxV = std::numeric_limits<T>::max();
  44     constexpr T minV = std::numeric_limits<T>::min();
  45
  46 //  Things that can be compared exactly
  47     static_assert((std::midpoint(T(0), T(0))   == T(0)),   "");
  48     static_assert((std::midpoint(T(2), T(4))   == T(3)),   "");
  49     static_assert((std::midpoint(T(4), T(2))   == T(3)),   "");
  50     static_assert((std::midpoint(T(3), T(4))   == T(3.5)), "");
  51     static_assert((std::midpoint(T(0), T(0.4)) == T(0.2)), "");
  52
  53 //  Things that can't be compared exactly
  54     constexpr T pct = fp_error_pct<T>();
  55     assert((fptest_close_pct(std::midpoint(T( 1.3), T(11.4)), T( 6.35),    pct)));
  56     assert((fptest_close_pct(std::midpoint(T(11.33), T(31.45)), T(21.39),  pct)));
  57     assert((fptest_close_pct(std::midpoint(T(-1.3), T(11.4)), T( 5.05),    pct)));
  58     assert((fptest_close_pct(std::midpoint(T(11.4), T(-1.3)), T( 5.05),    pct)));
  59     assert((fptest_close_pct(std::midpoint(T(0.1),  T(0.4)),  T(0.25),     pct)));
  60
  61     assert((fptest_close_pct(std::midpoint(T(11.2345), T(14.5432)), T(12.88885),  pct)));
  62
  63 //  From e to pi
  64     assert((fptest_close_pct(std::midpoint(T(2.71828182845904523536028747135266249775724709369995),
  65                                       T(3.14159265358979323846264338327950288419716939937510)),
  66                                       T(2.92993724102441923691146542731608269097720824653752),  pct)));
  67
  68     assert((fptest_close_pct(std::midpoint(maxV, T(0)), maxV/2, pct)));
  69     assert((fptest_close_pct(std::midpoint(T(0), maxV), maxV/2, pct)));
  70     assert((fptest_close_pct(std::midpoint(minV, T(0)), minV/2, pct)));
  71     assert((fptest_close_pct(std::midpoint(T(0), minV), minV/2, pct)));
  72     assert((fptest_close_pct(std::midpoint(maxV, maxV), maxV,   pct)));
  73     assert((fptest_close_pct(std::midpoint(minV, minV), minV,   pct)));
  74     assert((fptest_close_pct(std::midpoint(maxV, minV), maxV/2, pct)));
  75     assert((fptest_close_pct(std::midpoint(minV, maxV), maxV/2, pct)));
  76
  77 //  Near the min and the max
  78     assert((fptest_close_pct(std::midpoint(maxV*T(0.75), maxV*T(0.50)),  maxV*T(0.625), pct)));
  79     assert((fptest_close_pct(std::midpoint(maxV*T(0.50), maxV*T(0.75)),  maxV*T(0.625), pct)));
  80     assert((fptest_close_pct(std::midpoint(minV*T(2),    minV*T(8)),     minV*T(5),     pct)));
  81
  82 //  Big numbers of different signs
  83     assert((fptest_close_pct(std::midpoint(maxV*T( 0.75),  maxV*T(-0.5)), maxV*T( 0.125), pct)));
  84     assert((fptest_close_pct(std::midpoint(maxV*T(-0.75),  maxV*T( 0.5)), maxV*T(-0.125), pct)));
  85
  86 //  Denormalized values
  87 //  TODO
  88
  89 //  Check two values "close to each other"
  90     T d1 = T(3.14);
  91     T d0 = std::nextafter(d1, T(2));
  92     T d2 = std::nextafter(d1, T(5));
  93     assert(d0 < d1);  // sanity checking
  94     assert(d1 < d2);  // sanity checking
  95
  96 #if defined(__PPC__) && (defined(__LONG_DOUBLE_128__) && __LONG_DOUBLE_128__) &&                                       \
  97     !(defined(__LONG_DOUBLE_IEEE128__) && __LONG_DOUBLE_IEEE128__)
  98 //  For 128 bit long double implemented as 2 doubles on PowerPC,
  99 //  nextafterl() of libm gives imprecise results which fails the
 100 //  midpoint() tests below. So skip the test for this case.
 101     if constexpr (sizeof(T) != 16)
 102 #endif
 103     {
 104     //  Since there's nothing in between, the midpoint has to be one or the other
 105         T res;
 106         res = std::midpoint(d0, d1);
 107         assert(res == d0 || res == d1);
 108         assert(d0 <= res);
 109         assert(res <= d1);
 110         res = std::midpoint(d1, d0);
 111         assert(res == d0 || res == d1);
 112         assert(d0 <= res);
 113         assert(res <= d1);
 114
 115         res = std::midpoint(d1, d2);
 116         assert(res == d1 || res == d2);
 117         assert(d1 <= res);
 118         assert(res <= d2);
 119         res = std::midpoint(d2, d1);
 120         assert(res == d1 || res == d2);
 121         assert(d1 <= res);
 122         assert(res <= d2);
 123     }
 124 }
 125
 126
 127 int main (int, char**)
 128 {
 129     fp_test<float>();
 130     fp_test<double>();
 131     fp_test<long double>();
 132
 133     return 0;
 134 }