Constexpr version of c++ square root (for doubles)

constexpr_sqrt.cpp

#include <limits>	
	
namespace Detail
{
	double constexpr sqrtNewtonRaphson(double x, double curr, double prev)
	{
		return curr == prev
			? curr
			: sqrtNewtonRaphson(x, 0.5 * (curr + x / curr), curr);
	}
}

/*
* Constexpr version of the square root
* Return value:
*	- For a finite and non-negative value of "x", returns an approximation for the square root of "x"
*   - Otherwise, returns NaN
*/
double constexpr sqrt(double x)
{
	return x >= 0 && x < std::numeric_limits<double>::infinity()
		? Detail::sqrtNewtonRaphson(x, x, 0)
		: std::numeric_limits<double>::quiet_NaN();
}