quadmath_cpp provides C++ overloads for __float128 and <quadmath.h> functions. This allows you to use <quadmath.h> in templated functions. Instead of calling sinq(x) or powq(x, y), you can now call sin(x) or pow(x, y) just like you would with float or double.

quadmath_cpp also includes functions not present in <quadmath.h>, such as islessgreater(x, y) and fpclassify(x) from C++11, in addition to a few C23 functions like iseqsig(x, y).

Include the quadmath_cpp.h header in your code to use it. The header should compile fine on GCC from C++98 to C++23

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If you want to bring quadmath_cpp into the std:: namespace, define QUADMATH_CPP_NAMESPACE_STD to non-zero before including the header.

#define QUADMATH_CPP_NAMESPACE_STD 1
#include "quadmath_cpp.h"

This will allow you to call std::sin(x) and std::pow(x, y). However, extending the std:: namespace is undefined behaviour, so take caution with this feature.