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FEGETENV(3) FreeBSD 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.
However, 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 current
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
intermediate 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.