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FreeBSD 11.0 - man page for feholdexcept (freebsd section 3)

FEGETENV(3)						   BSD Library Functions Manual 					       FEGETENV(3)

fegetenv, feholdexcept, fesetenv, feupdateenv -- floating-point environment save and restore
Math Library (libm, -lm)
#include <fenv.h> #pragma STDC FENV_ACCESS ON int fegetenv(fenv_t *envp); int feholdexcept(fenv_t *envp); int fesetenv(const fenv_t *envp); int feupdateenv(const fenv_t *envp);
The floating-point environment includes exception flags and masks, the current rounding mode, and other architecture-specific settings. How- ever, it does not include the floating-point register file. The fegetenv() function stores the current floating-point environment in the object pointed to by envp, whereas feholdexcept() saves the cur- rent environment, then clears all exception flags and masks all floating-point exceptions. The fesetenv() function restores a previously saved environment. The feupdateenv() function restores a saved environment as well, but it also raises any exceptions that were set in the environment it replaces. The feholdexcept() function is often used with feupdateenv() or fesetenv() to suppress spurious exceptions that occur as a result of interme- diate computations. An example in fenv(3) demonstrates how to do this.
The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions return 0 if they succeed, and non-zero otherwise.
feclearexcept(3), fenv(3), feraiseexcept(3), fesetenv(3), fetestexcept(3), fpgetmask(3), fpgetprec(3), fpsetmask(3), fpsetprec(3)
The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions conform to ISO/IEC 9899:1999 (``ISO C99'').
These routines first appeared in FreeBSD 5.3.
May 8, 2004 BSD

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