With C99, the math.h header file defines two types:
These types are at least as wide as float and double respectively, and double_t is at least as wide as float_t. These are intended to be the most efficient types for doing float and double calculations, respectively.
This header file also defines several macros, as described in Table RS.V.13; all but HUGE_VAL are C99 additions. Some of these are discussed in more detail in Reference Section VIII, “C99 Numeric Computational Enhancements.”
|HUGE_VAL||A positive double constant not necessarily expressible as a float; in the past, it was used as the return value for functions when the magnitude of the result exceeded ...|