<ctgmath>
In effect, includes the Standard C++ library headers <ccomplex> and <cmath>, which provide type-generic math macros equivalent to <tgmath.h>.
#include <ctgmath>
Remarks
The functionality of the Standard C library header <tgmath.h> is provided by overloads in <ccomplex> and <cmath>.
Including this header ensures that the names declared using external linkage in the Standard C library header are declared in the std namespace.
See Also
Reference
Thread Safety in the C++ Standard Library