Macro constant that expands to a positive expression of type long double.
A function returns this value when the result of a mathematical operation yields a value that is too large in magnitude to be representable with its return type. This is one of the possible range errors, and is signaled by setting errno to ERANGE.
Actually, functions may either return a positive or a negative HUGE_VALL (HUGE_VALL or -HUGE_VALL) to indicate the sign of the result.