Function test_numtraits

dependence/eigen-3.4.0/test/bfloat16_float.cpp:172–208

}

void test_numtraits()
{
  std::cout << "epsilon       = " << NumTraits<bfloat16>::epsilon() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>(NumTraits<bfloat16>::epsilon()) << ")" << std::endl;
  std::cout << "highest       = " << NumTraits<bfloat16>::highest() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>(NumTraits<bfloat16>::highest()) << ")" << std::endl;
  std::cout << "lowest        = " << NumTraits<bfloat16>::lowest() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>(NumTraits<bfloat16>::lowest()) << ")" << std::endl;
  std::cout << "min           = " << (std::numeric_limits<bfloat16>::min)() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>((std::numeric_limits<bfloat16>::min)()) << ")" << std::endl;
  std::cout << "denorm min    = " << (std::numeric_limits<bfloat16>::denorm_min)() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>((std::numeric_limits<bfloat16>::denorm_min)()) << ")" << std::endl;
  std::cout << "infinity      = " << NumTraits<bfloat16>::infinity() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>(NumTraits<bfloat16>::infinity()) << ")" << std::endl;
  std::cout << "quiet nan     = " << NumTraits<bfloat16>::quiet_NaN() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>(NumTraits<bfloat16>::quiet_NaN()) << ")" << std::endl;
  std::cout << "signaling nan = " << std::numeric_limits<bfloat16>::signaling_NaN() << "  (0x" << std::hex << numext::bit_cast<numext::uint16_t>(std::numeric_limits<bfloat16>::signaling_NaN()) << ")" << std::endl;

  VERIFY(NumTraits<bfloat16>::IsSigned);

  VERIFY_IS_EQUAL(
    numext::bit_cast<numext::uint16_t>(std::numeric_limits<bfloat16>::infinity()),
    numext::bit_cast<numext::uint16_t>(bfloat16(std::numeric_limits<float>::infinity())) );
  // There is no guarantee that casting a 32-bit NaN to bfloat16 has a precise
  // bit pattern.  We test that it is in fact a NaN, then test the signaling
  // bit (msb of significand is 1 for quiet, 0 for signaling).
  const numext::uint16_t BFLOAT16_QUIET_BIT = 0x0040;
  VERIFY(
    (numext::isnan)(std::numeric_limits<bfloat16>::quiet_NaN())
    && (numext::isnan)(bfloat16(std::numeric_limits<float>::quiet_NaN()))
    && ((numext::bit_cast<numext::uint16_t>(std::numeric_limits<bfloat16>::quiet_NaN()) & BFLOAT16_QUIET_BIT) > 0)
    && ((numext::bit_cast<numext::uint16_t>(bfloat16(std::numeric_limits<float>::quiet_NaN())) & BFLOAT16_QUIET_BIT) > 0) );
  // After a cast to bfloat16, a signaling NaN may become non-signaling. Thus,
  // we check that both are NaN, and that only the `numeric_limits` version is
  // signaling.
  VERIFY(
    (numext::isnan)(std::numeric_limits<bfloat16>::signaling_NaN())
    && (numext::isnan)(bfloat16(std::numeric_limits<float>::signaling_NaN()))
    && ((numext::bit_cast<numext::uint16_t>(std::numeric_limits<bfloat16>::signaling_NaN()) & BFLOAT16_QUIET_BIT) == 0) );

  VERIFY( (std::numeric_limits<bfloat16>::min)() > bfloat16(0.f) );
  VERIFY( (std::numeric_limits<bfloat16>::denorm_min)() > bfloat16(0.f) );
  VERIFY_IS_EQUAL( (std::numeric_limits<bfloat16>::denorm_min)()/bfloat16(2), bfloat16(0.f) );
}

void test_arithmetic()
{