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fegetenv(3) [freebsd man page]

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

NAME
fegetenv, feholdexcept, fesetenv, feupdateenv -- floating-point environment save and restore LIBRARY
Math Library (libm, -lm) SYNOPSIS
#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); DESCRIPTION
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. RETURN VALUES
The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions return 0 if they succeed, and non-zero otherwise. SEE ALSO
feclearexcept(3), fenv(3), feraiseexcept(3), fesetenv(3), fetestexcept(3), fpgetmask(3), fpgetprec(3), fpsetmask(3), fpsetprec(3) STANDARDS
The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions conform to ISO/IEC 9899:1999 (``ISO C99''). HISTORY
These routines first appeared in FreeBSD 5.3. BSD
May 8, 2004 BSD

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

NAME
fegetenv, feholdexcept, fesetenv, feupdateenv -- functions providing access to the floating-point environment. SYNOPSIS
#include <fenv.h> #pragma STDC FENV_ACCESS ON int fegetenv(fenv_t *envp); int feholdexcept(fenvt_t *envp); int fesetenv(fenv_t *envp); int feupdateenv(fenv_t *envp); DESCRIPTION
These functions provide the means to manage the entire floating-point environment--including both status flags and control modes--as a single entity. The fegetenv() function attempts to store the current floating-point environment in the object pointed to by envp. It returns zero if the environment was successfully stored, and a nonzero value otherwise. The feholdexcept() function saves the current floating-point environment in the object pointed to by envp, clears the floating-point status flags, and then installs a "non-stop" mode, if available, under which no traps are taken for floating-point exceptions (as is the case in default IEEE-754 floating-point execution). It returns zero if and only if such a mode was successfully installed. The fesetenv() function attempts to establish the floating-point environment represented by the object pointed to by envp. This object shall have been set by a call to fegetenv() or feholdexcept(), or be equal to a floating-point environment macro defined in <fenv.h>. Note that this function merely installs the floating-point status flags represented by its argument, and does not raise the corresponding floating- point exceptions. It returns zero if and only if the environment pointed to by envp was successfully installed. The feupdateenv() function attempts to save the currently raised floating-point flags, install the floating-point environment represented by *envp, and then raise the floating-point exceptions corresponding to the saved flags. The object pointed to by envp shall have been set by a call to fegetenv() or feholdexcept(), or be equal to a floating-point environment macro defined in <fenv.h>. It returns zero if and only if all of the specified actions were successfully carried out. SEE ALSO
fenv(3), feclearexcept(3), fegetexceptflag(3), fegetround(3), feraiseexcept(3), fesetexceptflag(3), fesetround(3), feraiseexcept(3) STANDARDS
These functions conform to ISO/IEC 9899:TC3. BSD
May 9, 2011 BSD

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