libcxx/test/std/numerics/c.math/lerp.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 // UNSUPPORTED: c++03, c++11, c++14, c++17
   9 // <cmath>
  10
  11 // constexpr float lerp(float a, float b, float t) noexcept;
  12 // constexpr double lerp(double a, double b, double t) noexcept;
  13 // constexpr long double lerp(long double a, long double b, long double t) noexcept;
  14
  15 #include <cmath>
  16 #include <limits>
  17 #include <type_traits>
  18 #include <cassert>
  19
  20 #include "test_macros.h"
  21 #include "fp_compare.h"
  22
  23 template <typename T>
  24 constexpr bool constexpr_test()
  25 {
  26     return std::lerp(T( 0), T(12), T(0))   == T(0)
  27         && std::lerp(T(12), T( 0), T(0.5)) == T(6)
  28         && std::lerp(T( 0), T(12), T(2))   == T(24);
  29 }
  30
  31
  32 template <typename T>
  33 void test()
  34 {
  35     ASSERT_SAME_TYPE(T, decltype(std::lerp(T(), T(), T())));
  36     LIBCPP_ASSERT_NOEXCEPT(      std::lerp(T(), T(), T()));
  37
  38 //     constexpr T minV = std::numeric_limits<T>::min();
  39     constexpr T maxV = std::numeric_limits<T>::max();
  40     constexpr T inf  = std::numeric_limits<T>::infinity();
  41
  42 //  Things that can be compared exactly
  43     assert((std::lerp(T( 0), T(12), T(0)) == T(0)));
  44     assert((std::lerp(T( 0), T(12), T(1)) == T(12)));
  45     assert((std::lerp(T(12), T( 0), T(0)) == T(12)));
  46     assert((std::lerp(T(12), T( 0), T(1)) == T(0)));
  47
  48     assert((std::lerp(T( 0), T(12), T(0.5)) == T(6)));
  49     assert((std::lerp(T(12), T( 0), T(0.5)) == T(6)));
  50     assert((std::lerp(T( 0), T(12), T(2))   == T(24)));
  51     assert((std::lerp(T(12), T( 0), T(2))   == T(-12)));
  52
  53     assert((std::lerp(maxV, maxV/10, T(0)) == maxV));
  54     assert((std::lerp(maxV/10, maxV, T(1)) == maxV));
  55
  56     assert((std::lerp(T(2.3), T(2.3), inf) == T(2.3)));
  57
  58     assert(std::lerp(T( 0), T( 0), T(23)) ==  T(0));
  59     assert(std::isnan(std::lerp(T( 0), T( 0), inf)));
  60 }
  61
  62
  63 int main(int, char**)
  64 {
  65     static_assert(constexpr_test<float>(), "");
  66     static_assert(constexpr_test<double>(), "");
  67     static_assert(constexpr_test<long double>(), "");
  68
  69     test<float>();
  70     test<double>();
  71     test<long double>();
  72
  73     return 0;
  74 }