B.5 Floating-point environment <fenv.h>

fenv_t                 FE_OVERFLOW             FE_TOWARDZERO
fexcept_t              FE_UNDERFLOW            FE_UPWARD
FE_DIVBYZERO           FE_ALL_EXCEPT           FE_DFL_ENV
FE_INEXACT             FE_DOWNWARD
FE_INVALID             FE_TONEAREST

#pragma STDC FENV_ACCESS on-off-switch

int feclearexcept(int excepts);
int fegetexceptflag(fexcept_t *flagp, int excepts);
int feraiseexcept(int excepts);
int fesetexceptflag(const fexcept_t *flagp, int excepts);
int fetestexcept(int excepts);
int fegetround(void);
int fesetround(int round);
int fegetenv(fenv_t *envp);
int feholdexcept(fenv_t *envp);
int fesetenv(const fenv_t *envp);
int feupdateenv(const fenv_t *envp);