29 Numerics library [numerics]

29.9 Mathematical functions for floating-point types [c.math]

29.9.4 Classification / comparison functions [c.math.fpclass]

The classification / comparison functions behave the same as the C macros with the corresponding names defined in the C standard library.
Each function is overloaded for the three floating-point types.
See also: ISO C 7.
12.
3, 7.
12.
4