Function exp

include/half.hpp:2935–2961

Exponential function. This function is exact to rounding for all rounding modes. See also:** Documentation for [std::exp](https://en.cppreference.com/w/cpp/numeric/math/exp). \param arg function argument \return e raised to \a arg \exception FE_INVALID for signaling NaN \exception FE_OVERFLOW, ...UNDERFLOW, ...INEXACT according to rounding

	/// \exception FE_INVALID for signaling NaN
	/// \exception FE_OVERFLOW, ...UNDERFLOW, ...INEXACT according to rounding
	inline half exp(half arg)
	{
	#ifdef HALF_ARITHMETIC_TYPE
		return half(detail::binary, detail::float2half<half::round_style>(std::exp(detail::half2float<detail::internal_t>(arg.data_))));
	#else
		int abs = arg.data_ & 0x7FFF;
		if(!abs)
			return half(detail::binary, 0x3C00);
		if(abs >= 0x7C00)
			return half(detail::binary, (abs==0x7C00) ? (0x7C00&((arg.data_>>15)-1U)) : detail::signal(arg.data_));
		if(abs >= 0x4C80)
			return half(detail::binary, (arg.data_&0x8000) ? detail::underflow<half::round_style>() : detail::overflow<half::round_style>());
		detail::uint32 m = detail::multiply64(static_cast<detail::uint32>((abs&0x3FF)+((abs>0x3FF)<<10))<<21, 0xB8AA3B29);
		int e = (abs>>10) + (abs<=0x3FF), exp;
		if(e < 14)
		{
			exp = 0;
			m >>= 14 - e;
		}
		else
		{
			exp = m >> (45-e);
			m = (m<<(e-14)) & 0x7FFFFFFF;
		}
		return half(detail::binary, detail::exp2_post<half::round_style,true>(detail::exp2(m, 26), exp, (arg.data_&0x8000)!=0));
	#endif
	}

	/// Binary exponential.
	/// This function is exact to rounding for all rounding modes.