glm/glm/detail/func_exponential.inl

///////////////////////////////////////////////////////////////////////////////////
/// OpenGL Mathematics (glm.g-truc.net)
///
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/// all copies or substantial portions of the Software.
/// 
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/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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/// THE SOFTWARE.
///
/// @ref core
/// @file glm/core/func_exponential.inl
/// @date 2008-08-03 / 2011-06-15
/// @author Christophe Riccio
///////////////////////////////////////////////////////////////////////////////////

#include "func_vector_relational.hpp"
#include "_vectorize.hpp"
#include <limits>
#include <cassert>

namespace glm
{
	// pow
	template <typename genType>
	GLM_FUNC_QUALIFIER genType pow
	(
		genType const & x, 
		genType const & y
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'pow' only accept floating-point inputs");

		return std::pow(x, y);
	}

	VECTORIZE_VEC_VEC(pow)

	// exp
	template <typename genType>
	GLM_FUNC_QUALIFIER genType exp
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'exp' only accept floating-point inputs");

		return std::exp(x);
	}

	VECTORIZE_VEC(exp)

	// log
	template <typename genType>
	GLM_FUNC_QUALIFIER genType log
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'log' only accept floating-point inputs");

		return std::log(x);
	}

	VECTORIZE_VEC(log)

	//exp2, ln2 = 0.69314718055994530941723212145818f
	template <typename genType>
	GLM_FUNC_QUALIFIER genType exp2
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'exp2' only accept floating-point inputs");

		return std::exp(static_cast<genType>(0.69314718055994530941723212145818) * x);
	}

	VECTORIZE_VEC(exp2)

namespace detail
{
	template <bool isFloat>
	struct compute_log2
	{
		template <typename T>
		T operator() (T const & Value) const;
	};

	template <>
	struct compute_log2<true>
	{
		template <typename T>
		T operator() (T const & Value) const
		{
			return static_cast<T>(::std::log(Value)) * static_cast<T>(1.4426950408889634073599246810019);
		}
	};

}//namespace detail

	// log2, ln2 = 0.69314718055994530941723212145818f
	template <typename genType>
	GLM_FUNC_QUALIFIER genType log2
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(std::numeric_limits<genType>::is_iec559 || std::numeric_limits<genType>::is_integer,
			"GLM core 'log2' only accept floating-point inputs. Include <glm/gtx/integer.hpp> for additional integer support.");

		assert(x > genType(0)); // log2 is only defined on the range (0, inf]
		return detail::compute_log2<std::numeric_limits<genType>::is_iec559>()(x);
	}

	VECTORIZE_VEC(log2)

	// sqrt
	template <typename genType>
	GLM_FUNC_QUALIFIER genType sqrt
	(
		genType const & x
	)
	{
		GLM_STATIC_ASSERT(
			std::numeric_limits<genType>::is_iec559,
			"'sqrt' only accept floating-point inputs");

		assert(x >= genType(0));

		return std::sqrt(x);
	}

	VECTORIZE_VEC(sqrt)

	namespace detail
	{
		template <template <class, precision> class vecType, typename T, precision P>
		struct compute_inversesqrt
		{
			static vecType<T, P> call(vecType<T, P> const & x)
			{
				return static_cast<T>(1) / sqrt(x);
			}
		};
		
		template <template <class, precision> class vecType>
		struct compute_inversesqrt<vecType, float, lowp>
		{
			static vecType<float, lowp> call(vecType<float, lowp> const & x)
			{
				vecType<float, lowp> tmp(x);
				vecType<float, lowp> xhalf(tmp * 0.5f);
				vecType<uint, lowp> i = *reinterpret_cast<vecType<uint, lowp>*>(const_cast<vecType<float, lowp>*>(&x));
				i = vecType<uint, lowp>(0x5f375a86) - (i >> vecType<uint, lowp>(1));
				tmp = *reinterpret_cast<vecType<float, lowp>*>(&i);
				tmp = tmp * (1.5f - xhalf * tmp * tmp);
				return tmp;
			}
		};
	}//namespace detail
	
	// inversesqrt
	GLM_FUNC_QUALIFIER float inversesqrt(float const & x)
	{
		return 1.0f / sqrt(x);
	}
	
	GLM_FUNC_QUALIFIER double inversesqrt(double const & x)
	{
		return 1.0 / sqrt(x);
	}
	
	template <template <class, precision> class vecType, typename T, precision P>
	GLM_FUNC_QUALIFIER vecType<T, P> inversesqrt
	(
		vecType<T, P> const & x
	)
	{
		GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'inversesqrt' only accept floating-point inputs");
		return detail::compute_inversesqrt<vecType, T, P>::call(x);
	}

	VECTORIZE_VEC(inversesqrt)
}//namespace glm